Automatic merge from submit-queue (batch tested with PRs 45949, 46009, 46320, 46423, 46437)

Implement audit policy logic

Includes https://github.com/kubernetes/kubernetes/pull/45315#discussion_r117115932 (ignore the first commit)

Feature: https://github.com/kubernetes/features/issues/22

Remaining work:

- [x] Load the policy into the `server.Config`
- [x] Rebase on https://github.com/kubernetes/kubernetes/pull/45315
- [x] Establish shared code for audit api scheme (with https://github.com/kubernetes/kubernetes/pull/45919)
- [x] Once https://github.com/kubernetes/kubernetes/pull/45766 is merged, call the policy checker in the audit path

/cc @sttts @soltysh @ericchiang @ihmccreery @pweil- @deads2k