Automatic merge from submit-queue
StatefulSet scale subresource
**What this PR does / why we need it**: This PR implements scale subresource for StatefulSet.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#46005
**Special notes for your reviewer**:
**Release note**:
```release-note
StatefulSet uses scale subresource when scaling in accord with ReplicationController, ReplicaSet, and Deployment implementations.
```
**Feature Checklist**:
- [x] Introduce Registry interface for storage purpose
- [x] Introduce `ScaleREST New(), Get() and Update()` utility functions
- [x] Create a `ScaleREST` object at `NewREST()` and return it
- [x] Enable scale subresource by adding `/scale` field to the storage map
**Testing Checklist**:
- Unit testing
- [x] Modify `newStorage()` to call `NewStorage()`, and change all unit tests accordingly
- [x] Add unit tests for `ScaleREST Get() and Update()` utility functions
- [x] Add missing unit test for `ShortNames`
- Manual testing
- [x] Verify existence of the subresource using `kubectl proxy` command
- [x] Modify the subresource using `curl` via `POST`
- e2e testing
- [x] Add e2e tests using `RESTClient`
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