Automatic merge from submit-queue.
Manual cherrypick of kube-openapi changes for release-1.10
**What this PR does / why we need it**:
Cherry-picks kubernetes/kube-openapi#64 and kubernetes/kube-openapi#67
Fixes bugs that make apiserver panic when aggregating valid but not well formed OpenAPI spec (with empty `Paths`/`Definitions`)
**Release note**:
```release-note
Fixes bugs that make apiserver panic when aggregating valid but not well formed OpenAPI spec
```
/cc @MaciekPytel
/sig api-machinery
Kubernetes-commit: 42b63c8b19d1ad96399ec3f5a409da67e2fd19bd
Automatic merge from submit-queue (batch tested with PRs 55004, 54957). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Update kube-openapi to use validation
**What this PR does / why we need it**: Moves openapi validation code to kube-openapi, so that we can move the rest of the code to apimachinery repository, so that later we can use it from both the client and the server.
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #Nothing
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
Kubernetes-commit: 55e216f56eac0082acc6be655d9ae09cf9ba38a8
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
sample-controller: add example CRD controller
**What this PR does / why we need it**:
Adds a sample-controller example repository
fixes#52752
**Special notes for your reviewer**:
This is currently based on the sttts:sttts-codegen-scripts branch and should not be merged until that is (ref https://github.com/kubernetes/kubernetes/pull/52186)
**Release note**:
```
Add sample-controller repository
```
/cc @sttts @nikhita @colemickens
Kubernetes-commit: 9a7800f7d2efb88b397674672ac56f898826cf7c
Kubernetes Publisher