Automatic merge from submit-queue (batch tested with PRs 35094, 42095, 42059, 42143, 41944)
Fix azure file secret reference
Follow up to https://github.com/kubernetes/kubernetes/pull/41957
Fixes nil dereference getting secret name from AzureFile volume source.
Adds unit tests to make sure all secret references are extracted correctly, and adds reflective tests to help catch drift if new secret references are added to the pod spec