dsinstance: conn management
Connect and/or disconnect api.Backend.ldap2 connection when directory
server is stopped/restarted. Checking is ldap2 connection is connected
is neccesary for edge cases during ds installation (initial start).
https://fedorahosted.org/freeipa/ticket/6461
Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>