Automatic merge from submit-queue (batch tested with PRs 43777, 44121)
Add patchMergeKey and patchStrategy support to OpenAPI
Support generating Open API extensions for strategic merge patch tags in go struct tags
Support `patchStrategy` and `patchMergeKey`.
Also support checking if the Open API extension and struct tags match.
```release-note
Support generating Open API extensions for strategic merge patch tags in go struct tags
```
cc: @pwittrock @ymqytw
(Description mostly copied from #43833)
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