When keystone updates its relation data for the identity-service
relations, reactive charms need to be aware that an update occurred.
This change will add a new state (identity-service.available.updated).
Change-Id: Ic307f37f0ba861fb6b5f7d724565dea93c85906c
Closes-Bug: #1825951
Expose project and user domain and id information.
Depends-On: I228ddfbef23ab77885b093c8d5f359eec13d210c
Change-Id: I82b852218c08bfb397f20fa6289c149aad9d5cec