Add visibility filter to datastore versions

Allows datastore versions to be hidden from all users except those
explicitly allowed by their tenant. Implemented via a visibility
attribute for datastore versions (defaulting to 'public'), and a
datastore version member table for controlling access to non-public
datastore versions by tenant.

This commit provides the client functionality for integration tests
related to the datastore-visibility feature.

Implements: blueprint datastore-visibility
Docimpact: change to datastore version payload
Change-Id: Ic8024a631530ba295688d7e49e895f50cb2f32ef
Merge "Add visibility filter to datastore versions"