Automatic merge from submit-queue (batch tested with PRs 55557, 55504, 56269, 55604, 56202). 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>.
Create{Container,Pod}SecurityContext: modify a pod and don't return the annotations
**What this PR does / why we need it**:
Prior https://github.com/kubernetes/kubernetes/pull/52849 we couldn't modify a pod and had to return annotations from the methods. But now, as we always working with a copy of a pod, we can modify it directly and we don't need to copy&return annotations separately.
This PR simplifies the code by modifying a pod directly. Also it renames these methods and replaces returning of the `SecurityContext` by in-place modification.
In fact it reverts the changes from https://github.com/kubernetes/kubernetes/pull/30257
**Release note**:
```release-note
NONE
```
PTAL @liggitt @timstclair
CC @simo5
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>.
pkg/api: extract Scheme/Registry/Codecs into pkg/api/legacyscheme
This serves as
- a preparation for the pkg/api->pkg/apis/core move
- and makes the dependency to the scheme explicit when vizualizing
left depenncies.
The later helps with our our efforts to split up the monolithic repo
into self-contained sub-repos, e.g. for kubectl, controller-manager
and kube-apiserver in the future.
this is a two stage refactor when done there will be no init block in admission plugins.
Instead all plugins expose Register function which accept admission.Plugins instance.
The registration to global plugin registry happens inside Register func.
