Add AWS CLI in order to ship library artifacts from container

[jmazanec15]

Issue #, if available:
#169

Description of changes:
Because we now build and ship library artifacts from Centos container, we need to manually install the AWS CLI in the container. Verified that this installation works on Centos 7.

Related to test Github action failure: https://github.com/opendistro-for-elasticsearch/k-NN/runs/951599939?check_suite_focus=true

Documentation for installing AWS CLI on linux: https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2-linux.html

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov]

Codecov Report

Merging #194 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #194   +/-   ##
=========================================
  Coverage     78.35%   78.35%           
  Complexity      307      307           
=========================================
  Files            49       49           
  Lines          1141     1141           
  Branches        100      100           
=========================================
  Hits            894      894           
  Misses          198      198           
  Partials         49       49           

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[vamshin]

Why do we need AWS cli?

[jmazanec15]

@vamshin we need it because we use it to copy the built artifacts to S3 here. The Centos container used for building the artifacts does not come with it, like the Github Actions Ubuntu runner.