This is an initial implementation of the /groups graph endpoint.
Currently it is only showing the ID and Name attributes of the groups.
Listing members is not yet supported.
As the userbackend this is still read-only and doesn't support any
advanced filtering.
This module basically wraps ldap.Client and allows us to keep
to keep a long running LDAP connection open, which automatically
reconnects on network errors. Allows it allows to easiliy multiplex
multiple Operations on a single connection.