Adds random password generation capability to demo config install scripts

[DarshitChanpura]

Description

As a follow to changes made in demo config script, this PR adds a script to generate a random 16 character password if the flag to generate random password -g is passed. It will only generate and set admin password when following conditions are true:

• initialAdminPassword variable is not set as env variable
• initialAdminPassword.txt doesn't exist
• -g flag is passed to the script

If -g is not passed and other two conditions are false, the install demo config script would fail.

Related to: #1576

Testing

Manual testing:

Windows install logs:

**************************************************************************
** This tool will be deprecated in the next major release of OpenSearch **
** https://github.com/opensearch-project/security/issues/1755           **
**************************************************************************

OpenSearch Security Demo Installer
 ** Warning: Do not use on production or public reachable systems **

Basedir: C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\
OpenSearch install type: .zip on Windows_NT
OpenSearch config dir: C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\config\
OpenSearch config file: C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\config\opensearch.yml
OpenSearch bin dir: C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\bin\
OpenSearch plugins dir: C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\plugins\
OpenSearch lib dir: C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\lib\
Detected OpenSearch Version: 3.0.0
Detected OpenSearch Security Version: 3.0.0.0
"what is in the config directory"  
 Volume in drive C has no label.
 Volume Serial Number is E61A-B1DE

 Directory of C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\config

10/05/2023  06:48 PM    <DIR>          .
10/05/2023  06:33 PM    <DIR>          ..
10/05/2023  06:48 PM             1,707 esnode-key.pem
10/05/2023  06:48 PM             1,532 esnode.pem
08/31/2023  03:27 PM             2,747 jvm.options
08/31/2023  03:27 PM    <DIR>          jvm.options.d
10/05/2023  06:48 PM             1,707 kirk-key.pem
10/05/2023  06:48 PM             1,658 kirk.pem
08/31/2023  03:27 PM            14,808 log4j2.properties
08/31/2023  05:37 PM    <DIR>          opensearch-security
08/31/2023  05:33 PM               196 opensearch.keystore
10/05/2023  06:48 PM             6,416 opensearch.yml
10/05/2023  06:48 PM             1,719 root-ca.pem
               9 File(s)         32,490 bytes
               4 Dir(s)  169,389,215,744 bytes free
"what is in the password file"
"   ***************************************************"
"   ***   ADMIN PASSWORD SET TO: BoXO6rWKjVJUqpUC  ***"
"   ***************************************************"
### Success
### Execute this script now on all your nodes and then start all nodes
### OpenSearch Security will be automatically initialized.
### If you like to change the runtime configuration 
### change the files in ../../../config/opensearch-security and execute: 
 
C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\plugins\opensearch-security\tools\securityadmin.bat -cd C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\config\opensearch-security -icl -key C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\config\kirk-key.pem -cert C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\config\kirk.pem -cacert C:\Users\Administrator\Documents\localDistro\opensearch-3.0.0-SNAPSHOT\config\root-ca.pem -nhnv 
### or run ./securityadmin_demo.bat
### To use the Security Plugin ConfigurationGUI
### [Ignore the SSL certificate warning because we installed self-signed demo certificates]

Windows curl ouput after password change:

C:\Users\Administrator>curl -XGET https://localhost:9200/ -k -u admin:admin
Unauthorized
C:\Users\Administrator>curl -XGET https://localhost:9200/ -k -u admin:BoXO6rWKjVJUqpUC
{
  "name" : "EC2AMAZ-SPV3HQH",
  "cluster_name" : "opensearch",
  "cluster_uuid" : "QhnbMcigR6KKTj-XZtr21w",
  "version" : {
    "distribution" : "opensearch",
    "number" : "3.0.0-SNAPSHOT",
    "build_type" : "zip",
    "build_hash" : "bb38ed4836496ac70258c2472668325a012ea3ed",
    "build_date" : "2023-08-31T15:25:32.930646600Z",
    "build_snapshot" : true,
    "lucene_version" : "9.8.0",
    "minimum_wire_compatibility_version" : "2.10.0",
    "minimum_index_compatibility_version" : "2.0.0"
  },
  "tagline" : "The OpenSearch Project: https://opensearch.org/"
}

Mac install_demo_config log:

➜  opensearch-security ./tools/install_demo_configuration.sh -y -i -s -g
./tools/install_demo_configuration.sh: line 3: ./generate-password.sh: No such file or directory
**************************************************************************
** This tool will be deprecated in the next major release of OpenSearch **
** https://github.com/opensearch-project/security/issues/1755           **
**************************************************************************
OpenSearch Security Demo Installer
 ** Warning: Do not use on production or public reachable systems **
Basedir: /Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT
OpenSearch install type: .tar.gz on
OpenSearch config dir: /Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/config
OpenSearch config file: /Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/config/opensearch.yml
OpenSearch bin dir: /Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/bin
OpenSearch plugins dir: /Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/plugins
OpenSearch lib dir: /Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/lib
Detected OpenSearch Version: x-content-3.0.0-SNAPSHOT
Detected OpenSearch Security Version: 3.0.0.0-SNAPSHOT

   ***************************************************
   ***   ADMIN PASSWORD SET TO: Mari4UfLQajoASVo    ***
   ***************************************************
**************************************************************************
** This tool will be deprecated in the next major release of OpenSearch **
** https://github.com/opensearch-project/security/issues/1755           **
**************************************************************************
### Success
### Execute this script now on all your nodes and then start all nodes
### OpenSearch Security will be automatically initialized.
### If you like to change the runtime configuration
### change the files in ../../../config/opensearch-security and execute:
"/Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/plugins/opensearch-security/tools/securityadmin.sh" -cd "/Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/config/opensearch-security" -icl -key "/Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/config/kirk-key.pem" -cert "/Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/config/kirk.pem" -cacert "/Users/dchanp/Documents/amazon/testing-playground/test/binaries/opensearch-3.0.0-SNAPSHOT/config/root-ca.pem" -nhnv
### or run ./securityadmin_demo.sh
### To use the Security Plugin ConfigurationGUI
### To access your secured cluster open https://<hostname>:<HTTP port> and log in with admin/admin.
### (Ignore the SSL certificate warning because we installed self-signed demo certificates)

Mac curl output after password change:

➜  ~ curl -XGET 'https://[::1]:9200/' -k -u admin:admin

Unauthorized%
➜  ~ curl -XGET 'https://[::1]:9200/' -k -u admin:Mari4UfLQajoASVo

{
  "name" : "3c06300b34da.ant.amazon.com",
  "cluster_name" : "opensearch",
  "cluster_uuid" : "Zw9pjloBTiiqzfusz2nyLQ",
  "version" : {
    "distribution" : "opensearch",
    "number" : "3.0.0-SNAPSHOT",
    "build_type" : "tar",
    "build_hash" : "d656e3db592f29466d35452867caa241f5429485",
    "build_date" : "2023-09-28T15:29:27.870375Z",
    "build_snapshot" : true,
    "lucene_version" : "9.8.0",
    "minimum_wire_compatibility_version" : "2.11.0",
    "minimum_index_compatibility_version" : "2.0.0"
  },
  "tagline" : "The OpenSearch Project: https://opensearch.org/"
}

Check List

• New functionality includes testing
  - [ ] New functionality has been documented
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[DarshitChanpura]

Closing this for now. Will re-open once demo configuration changes are finalized.