feat: add Active Directory connector with USN-based incremental sync

[kbering]

This commit introduces a new connector for Microsoft Active Directory with support for efficient incremental synchronization using Update Sequence Numbers (USN).

Features:

• Full sync of AD objects (users, groups, computers, OUs)
• USN-based incremental sync for efficient updates
• LDAPS support for secure connections
• NTLM and Simple authentication
• Configurable object type filtering
• Paged LDAP queries for large environments
• Comprehensive attribute mapping

Components:

• datasource.py: Main connector implementing BaseDataSource
• client.py: LDAP client wrapper with async support
• constants.py: AD schemas and attribute definitions
• test_active_directory.py: Unit and integration tests
• README.md: Complete documentation

Technical Details:

• Tracks highestCommittedUSN from AD
• Queries (uSNChanged >= last_usn) for changed objects
• Async implementation using ldap3 library
• Proper error handling and logging

Testing:

• Unit tests with mocked LDAP responses
• Integration tests for real AD environments
• pytest configuration included

Closes https://github.com/elastic/connectors-py/issues/###

Checklists

Pre-Review Checklist

• this PR does NOT contain credentials of any kind, such as API keys or username/passwords (double check config.yml.example)
• this PR has a meaningful title
• this PR links to all relevant github issues that it fixes or partially addresses
• if there is no GH issue, please create it. Each PR should have a link to an issue
• this PR has a thorough description
• Covered the changes with automated tests
• Tested the changes locally
• Added a label for each target release version (example: v7.13.2, v7.14.0, v8.0.0)
• For bugfixes: backport safely to all minor branches still receiving patch releases
• Considered corresponding documentation changes
• Contributed any configuration settings changes to the configuration reference
• if you added or changed Rich Configurable Fields for a Native Connector, you made a corresponding PR in Kibana

Changes Requiring Extra Attention

• Security-related changes (encryption, TLS, SSRF, etc)
• New external service dependencies added.

Related Pull Requests

Release Note

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[seanstory]

buildkite test this

[seanstory]

Hi @kbering, thanks for the contribution!

In order for us to consider merging this, you'll need to sign the Contributor License Agreement (CLA). This gives Elastic permission to use your code.

Next, we'll want to make sure we understand the use case for this connector. Why do you need an Active Directory connector? How do you plan to use this data once it's in Elasticsearch? Its important for us to not take on new connectors until we understand that they'd be useful for more than just one customer.

Finally, I've just kicked off a CI job for this branch. If it fails, we'll need to address those failures. EDIT: looks like the linter failed. Try running make autoformat, and then make lint locally. If that passes, commit and push those changes.

Thanks again for this work! We'll be looking forward to giving it a thorough review after the holidays.