Refactor LDAP request and reply system

This commit streamlines the handling of LDAP requests and replies. The previous system of using 'send', 'get' and 'cleanup' functions for LDAP requests has been replaced with a single 'ldap_search' function. This change simplifies the code base, improves maintainability and minimizes thread safety concerns by eliminating the need for separate request and reply functions along with the associated channel management.

Signed-off-by: Christian Roessner c@roessner.co