Partial LDAP sync for one OU or one user

## What

trigger a partial / targeted LDAP sync (one OU / one user) instead of always syncing the whole directory.

## Want

- Trigger a partial / targeted LDAP sync (one OU / one user) instead of always syncing the whole directory

## Ideas this came from

- [#9764 An option to sync LDAP sources partially](https://github.com/goauthentik/authentik/issues/9764) — We've been trying out Authentik for a while now and we're currently looking to integrate it within our current setup. We have an existing OpenLDAP service and w
- [#12134 Extend management commands to support "targeted" LDAP sync](https://github.com/goauthentik/authentik/issues/12134) — Authentik provides Django management commands for triggering an LDAP sync (implementend in authentik/sources/ldap/management/commands/ldapsync.py). These can on

Start by reading authentik/sources/ldap/management/commands/ldapsync.py and the linked issues #9764 and #12134 to understand the existing full-directory sync and requested targeting. Done means a sync can be triggered for one OU or one user instead of always processing the whole directory.

Written by the indexing model from the issue text.