Automatic merge from submit-queue (batch tested with PRs 46967, 46992, 43338, 46717, 46672)
Add group alias names to API resources to allow discovery
**What this PR does / why we need it**:
Adds `GroupNames []string` to API resources, which represents the list of group aliases that every resource belongs to.
Partially fixes https://github.com/kubernetes/kubernetes/issues/41353
This moves the logic of "all" (which currently [translates](fbc94c0896/pkg/kubectl/cmd/util/shortcut_restmapper.go (L106)) to "pods,replicationcontrollers,services,...") to the server-side. Will allow clients like `kubectl` to discover group aliases instead of having it hardcoded and the API server to better handle consistency across multiple clients, version skew, etc; and will make "all" un-special and allow other groups to be created.
As a follow-up we'll patch `kubectl` to make groups aliases discoverable and the hardcoded list a fallback while we still have to support it.
Related to https://github.com/kubernetes/kubernetes/pull/42595#issuecomment-286839885.
**Release note**:
```release-note
Adds the `Categories []string` field to API resources, which represents the list of group aliases (e.g. "all") that every resource belongs to.
```
@kubernetes/sig-api-machinery-misc @deads2k @bgrant0607
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