refactor: Switch from ldap_poller to a direct implementation

[tlater-famedly]

This cuts out an incredible amount of middle-man code that is completely unnecessary for famedly-sync in practice.

Also cleans up a couple of inherited bugs (like not correctly quitting if we run into a connection issue), and hopefully increases logging capacity. Basically, a prerequisite of famedly/ldap-poller#36, since this lets us reasonably fix the issue downstream.

TODO:

• Rewrite the currently sync bits with async code
  • Apparently ldap3 created a sync interface by just calling block_on-type things on their async methods, so it is completely incompatible with otherwise async code
• Check if this actually gives us more logs
  • Probably not actually necessary to merge this, it's good-to-have anyway
• Figure out what the deleted entries thing is about again
• Get the tests to pass
• Write some new tests to assert the new bits work well
• Cover error cases

[codecov]

Codecov Report

Attention: Patch coverage is 99.12281% with 1 line in your changes missing coverage. Please review.

Project coverage is 92.86%. Comparing base (5ab1845) to head (727c4d9).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/sources/ldap.rs	99.12%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #106      +/-   ##
==========================================
- Coverage   93.18%   92.86%   -0.32%     
==========================================
  Files           9        9              
  Lines        1716     1669      -47     
==========================================
- Hits         1599     1550      -49     
- Misses        117      119       +2     

Files with missing lines	Coverage Δ
src/sources/ldap.rs	96.79% <99.12%> (-1.07%)	⬇️

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