FIX: PHP8 fix for removed ldap functions

[michalkouril]

Description

LDAP sync failing in PHP8 (per #56, #35) due to removal of ldap_control_paged_result. The fix is to use ldap_search in PHP8+ only.

Manual testing steps

Tested in AD environment.

Issues

• PHP 8.x incompatibility #56,
• ldap_control_paged_result is deprecated in php 7.4 #35

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[forsdahl]

Quickly looking at this PR, it seems it also includes another commit for adding nested_groups_search_locations and user_filter configs. Could you @michalkouril split those out to a separate PR?