Jira: OSPRH-20525

This PR adds end-to-end support for consuming Keystone ApplicationCredentials (AC) in the Manila operator, enabling Manila API pods to use AC-based authentication when available.

Reconcile:

On each reconcile, the Manila API controller checks for an AC Secret (ac-{service}-secret) using the GetApplicationCredentialFromSecret() helper from keystone-operator API:

• If the secret is missing or incomplete, continues using password authentication
• Once the AC Secret is ready with valid AC_ID and AC_SECRET fields, templates AC credentials into Manila configuration
• Computes hash of Secret contents and stores in configVars to trigger rolling updates when credentials rotate

Depends-On: openstack-k8s-operators/keystone-operator#567