Automatic merge from submit-queue (batch tested with PRs 35300, 36709, 37643, 37813, 37697)
Add generated informers
Add informer-gen and the informers it generates. We'll do follow-up PRs to convert everything currently using the hand-written informers to the generated ones.
TODO:
- [x] switch to `GroupVersionResource`
- [x] finish godoc
@deads2k @caesarxuchao @sttts @liggitt