fix(cli): Inform user to install optional dependency on missing google.cloud

Importing `gcp_utils` during `adk create` caused a ModuleNotFoundError because `resourcemanager_v3` was imported at module level. Moved the import into `list_gcp_projects` function scope where ImportError is caught specifically to raise an informative RuntimeError indicating they need to install the 'gcp' optional dependency. Also added google-cloud-resource-manager to optional dependencies.

Fixes https://github.com/google/adk-python/issues/5766

Change-Id: I9469e03c72342730cd0a1418551305a5e8058f60