Reduce queries to LDAP by caching nested groups
Reduce queries to LDAP by caching nested groups

Nested groups are now cached in a CappedMemoryCache object to reduce
queries to the LDAP backend.

Signed-off-by: Roland Tapken <0d270388f2f92757a5de0f4bd891d3b392c44c4f@bitarbeiter.net>

andreas-p/nextcloud-server,nextcloud/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,nextcloud/server,nextcloud/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server