Fix and re-enable the ldap handler
The LDAP handler is currently disabled in defaults builds because it's broken.
We should drop the current code and implement a new one based on this version which is used by some contributors:
- helper: https://paste.sysnove.net/paste/qGUN3Ztl#Bj9gS4Zz
- handler: https://paste.sysnove.net/paste/9HozrSv0#R1aCSSS+
- example: https://paste.sysnove.net/paste/-MFnffKK#nXf7O4yM
(Also reported in DEBBUG-726115)
Edited by Jerome Charaoui