Add encrypted ldap secrets support

What does this MR do?

Add encrypted ldap secrets support

Adds a new ldap_secrets path setting for optional ldap secrets file. And adds a new set of ldap secrets rake commands for showing/editing an ldap secret

Adds support for loading ldap servers' password and/or user_bn from the encrypted secrets.

• documentation MR !48090 (merged)
• omnibus MR for generating the secret omnibus-gitlab!4687 (merged)
• charts MR for generating the secret gitlab-org/charts/gitlab!1617 (merged)
• adding to usage data MR !48210 (merged)

Part of #238483 (closed) and currently depends on !43220 (merged)

Usage

Users first need to ensure their secrets.yml has a encrypted_settings_key_base. This can be done by running a rake command with the optional generation opted int: bundle exec rake gitlab:env:info GITLAB_GENERATE_ENCRYPTED_SETTINGS_KEY_BASE=true

Then they can use the EDITOR=vim rake gitlab:ldap:secret:edit command to provide their ldap credentials. The expected input is to be yaml, with your credentials nested under your provider:

main:
  password: 'my-password'
  user_bn: 'my/user/bn'

Users can also create the file without an editor by piping to stdin of the rake gitlab:ldap:secret:write command.

cat my-plaintext-creds.yml | rake gitlab:ldap:secret:write

And users can see the credentials via rake gitlab:ldap:secret:show

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team