Automatic merge from submit-queue
[Federation] Implement leader election for controller-manager
**What this PR does / why we need it**:
- Add cluster-selector for namespace
- Add support for creating federation-only objects. - Ref #44631
- Implements leader election for controller-manager.
Ref: #44283
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#44490
**Special notes for your reviewer**:
This PR also fixes the issue #44490, which is about delay in initializing controller-manager due to unavailability of api-server.
**Release note**:
```release-note
federation: Support for leader-election among federation controller-manager instances introduced.
```
/cc @kubernetes/sig-federation-pr-reviews
d6c40d6ac3