Automatic merge from submit-queue (batch tested with PRs 51574, 51534, 49257, 44680, 48836)

Add a persistent volume label controller to the cloud-controller-manager

Part of https://github.com/kubernetes/features/issues/88

Outstanding concerns needing input:
- [x] Why 5 threads for controller processing?
- [x] Remove direct linkage to aws/gce cloud providers [#51629]
- [x] Modify shared informers to allow added event handlers ability to include uninitialized objects/using unshared informer #48893
- [x] Use cache.MetaNamespaceKeyFunc in event handler?

I'm willing to work on addressing the removal of the direct linkage to aws/gce after this PR gets in.