Rename following (global) envvars to be inline with the naming convention

[mmattel]

Refernces:
#4932 (Env vars in webdav service start with REVA_ and not with OCIS_)
#3917 (Harmonize env variable naming for those which are not bound to a particular service)
https://doc.owncloud.com/ocis/next/deployment/services/env-vars-special-scope.html

Some envvars need naming harmonisation to align with the namespace used which makes them future proof. This should be addressed as this gets very hard later on.

No technical obstacles on renaming the LDAP envvars as discussed with @rhafer.

The list shows which are affected and how they should be named:

Global Envvars

• ACCOUNTS_DEMO_USERS_AND_GROUPS --> OCIS_ACCOUNTS_DEMO_USERS_AND_GROUPS
• LDAP_BIND_DN --> OCIS_LDAP_BIND_DN
• LDAP_BIND_PASSWORD --> OCIS_LDAP_BIND_PASSWORD
• LDAP_DISABLE_USER_MECHANISM --> OCIS_LDAP_DISABLE_USER_MECHANISM
  graph: Allow disabling user by adding to local group #5625
  Configure user disable mechanism in reva. #5692
• LDAP_DISABLED_USERS_GROUP_DN --> OCIS_LDAP_DISABLED_USERS_GROUP_DN
  graph: Allow disabling user by adding to local group #5625
  Configure user disable mechanism in reva. #5692
• LDAP_CACERT --> OCIS_LDAP_CACERT
• LDAP_GROUP_BASE_DN --> OCIS_LDAP_GROUP_BASE_DN
• LDAP_GROUP_FILTER --> OCIS_LDAP_GROUP_FILTER
• LDAP_GROUP_OBJECTCLASS --> OCIS_LDAP_GROUP_OBJECTCLASS
• LDAP_GROUP_SCHEMA_DISPLAYNAME --> OCIS_LDAP_GROUP_SCHEMA_DISPLAYNAME
• LDAP_GROUP_SCHEMA_GROUPNAME --> OCIS_LDAP_GROUP_SCHEMA_GROUPNAME
• LDAP_GROUP_SCHEMA_ID --> OCIS_LDAP_GROUP_SCHEMA_ID
• LDAP_GROUP_SCHEMA_ID_IS_OCTETSTRING --> OCIS_LDAP_GROUP_SCHEMA_ID_IS_OCTETSTRING
• LDAP_GROUP_SCHEMA_MAIL --> OCIS_LDAP_GROUP_SCHEMA_MAIL
• LDAP_GROUP_SCHEMA_MEMBER --> OCIS_LDAP_GROUP_SCHEMA_MEMBER
• LDAP_GROUP_SCOPE --> OCIS_LDAP_GROUP_SCOPE
• LDAP_INSECURE --> OCIS_LDAP_INSECURE
• LDAP_EDUCATION_RESOURCES_ENABLED --> OCIS_LDAP_EDUCATION_RESOURCES_ENABLED
  (Graph education resource #5213)
• LDAP_SCHOOL_BASE_DN --> OCIS_LDAP_SCHOOL_BASE_DN
  (Graph education resource #5213)
• LDAP_SCHOOL_SCOPE --> OCIS_LDAP_SCHOOL_SCOPE
  (Graph education resource #5213)
• LDAP_SCHOOL_FILTER --> OCIS_LDAP_SCHOOL_FILTER
  (Graph education resource #5213)
• LDAP_SCHOOL_SCHEMA_SCHOOL_NUMBER --> OCIS_LDAP_SCHOOL_SCHEMA_SCHOOL_NUMBER
  (Graph education resource #5213)
• LDAP_URI --> OCIS_LDAP_URI
• LDAP_USER_BASE_DN --> OCIS_LDAP_USER_BASE_DN
• LDAP_USER_ENABLED_ATTRIBUTE --> OCIS_LDAP_USER_ENABLED_ATTRIBUTE
  (graph: Add accountEnabled flag to ldap backend. #5588)
• LDAP_USER_FILTER --> OCIS_LDAP_USER_FILTER
• LDAP_USER_OBJECTCLASS --> OCIS_LDAP_USER_OBJECTCLASS
• LDAP_USER_SCHEMA_DISPLAYNAME --> OCIS_LDAP_USER_SCHEMA_DISPLAYNAME
• LDAP_USER_SCHEMA_ID --> OCIS_LDAP_USER_SCHEMA_ID
• LDAP_USER_SCHEMA_ID_IS_OCTETSTRING --> OCIS_LDAP_USER_SCHEMA_ID_IS_OCTETSTRING
• LDAP_USER_SCHEMA_MAIL --> OCIS_LDAP_USER_SCHEMA_MAIL
• LDAP_USER_SCHEMA_USERNAME --> OCIS_LDAP_USER_SCHEMA_USERNAME
• LDAP_USER_SCHEMA_USER_TYPE --> OCIS_LDAP_USER_SCHEMA_USER_TYPE
  (graph: Use userType property to distinguish between Member and Guest accounts #5800)
• LDAP_USER_SCOPE --> OCIS_LDAP_USER_SCOPE
• REVA_GATEWAY --> OCIS_REVA_GATEWAY
• STORAGE_TRANSFER_SECRET --> OCIS_STORAGE_TRANSFER_SECRET
• STORAGE_USERS_OCIS_ASYNC_UPLOADS --> OCIS_STORAGE_USERS_ASYNC_UPLOADS

In webdav the service

• REVA_GATEWAY_TLS_MODE --> OCIS_REVA_GATEWAY_TLS_MODE
• REVA_GATEWAY_TLS_CACERT --> OCIS_REVA_GATEWAY_TLS_CACERT

NOTES:

• For envvars in services, the change is easy as we have a working deprecation method which includes automation for the admin docs.
• For global envvars, these need manual deprecation (and removal). We have a list of occurrences in services where the changes need to be added too, see the link to the admin docs above.
  Admin docs need a manual created entry for these deprecations (not a big deal).
• Updating the admin docs outside services (not a big deal).
• Updating owncloud.dev accordingly.
• Updating the examples and helm charts.

Should be added to sprint.

@dragotin @micbar @wkloucek @butonic

[mmattel]

Just a sidenote, if one finds an envvar that begs for renaming - this is the chance to go for !