Support identity_version in credential provider wrappers

Add identity_version to get_client_manager and get_isolated_credentials.
Most tests rely on the configured version, which is the default if not
specified, but identity test need to force this to v2 or v3.

Change-Id: I69e07237c49e13bc1fd506e9decbbb27840a733b
Partially-implements: bp/multi-keystone-api-version-tests
2 files changed