The new keystone-k8s operator uses the application data bag and
more up-to-date key names for endpoint and authentication information.
Check for this information and then fallback to the existing
keystone charm unit data bag data set if not found.
Update register_endpoints to also provide new application data
bag JSON encoded data when this method is called from a lead
unit. This relies on the type and description of the endpoint
being provided which will require a charm change on adoption.
Change-Id: I921d173c64b12c35f5ffc17270a0fc2bb83891c4
1a5142bac6