API support for LDAP authentication

[szh]

Desired Outcome

Create a new implementation of the AuthenticationStrategy interface added in ONYX-20429 for authn-ldap. Include new unit tests and add a test case to the integration tests.

Implemented Changes

• Refactored AuthnAuthenticationStrategy to make it easier to extend it for LDAP support
• Created LdapAuthenticationStrategy which extends AuthnAuthenticationStrategy and adds a service_id and changes the api endpoint URLs.
• Added a test case to TestIntegrationVanila to test the LdapAuthenticationStrategy with an openldap server.

Connected Issue/Story

CyberArk internal issue link: ONYX-20430

Changelog

• [x] The CHANGELOG has been updated, or
• [ ] This PR does not include user-facing changes and doesn't require a CHANGELOG update

Test coverage

• [x] This PR includes new unit and integration tests to go with the code changes, or
• [ ] The changes in this PR do not require tests

Documentation

• [x] Docs (e.g. READMEs) were updated in this PR
• [ ] A follow-up issue to update official docs has been filed here: [insert issue ID]()
• [ ] This PR does not require updating any documentation

Behavior

• [ ] This PR changes product behavior and has been reviewed by a PO, or
• [x] These changes are part of a larger initiative that will be reviewed later, or
• [ ] No behavior was changed with this PR

Security

• [ ] Security architect has reviewed the changes in this PR,
• [x] These changes are part of a larger initiative with a separate security review, or
• [ ] There are no security aspects to these changes

[szh]

LGTTM!

@rpothier Thanks! I squashed the last two commits. Can you please reapprove?

[szh]

Also please take a look at this follow up PR in the CLI