LDAP socket connections may need additional code to set keepalive

LDAP routines that connect may need to set socket keepalive settings to prevent firewall disconnect after a few minutes of idle time.
This can theoretically be done via os tuneables config from aks create options, but it may not be working well or always available via terraform etc.
We can add code to ldaputils / ldapconnection to set the socket keepalive settings via either getting the socket fd and calling setsockopt() on it, or look into LDAP options:
LDAP_OPT_X_KEEPALIVE_INTERVAL