Charge object count when object is created, no matter if the object is
initialized or not.
Charge the remaining quota when the object is initialized.
Also, checking initializer.Pending and initializer.Result when
determining if an object is initialized. We didn't need to check them
because before 51082, having 0 pending initializer and nil
initializers.Result is invalid.
Automatic merge from submit-queue (batch tested with PRs 48576, 49010)
make externalAdmissionHookConfigurationManager distinguish API disabled error
The externalAdmissionHookConfigurationManager does not return "DisabledErr" even if the API is disabled, so the GenericWebhook admission controller will not fail open.
The GenericWebhook admission controller is default to off, so the bug is hidden in most cases. To be safe, we should cherrypick it to 1.7.
```release-note
Fix a bug where the GenericWebhook admission plugin does not fail open when the admissionregistration API is disabled
```
Handle failure cases on startup gracefully to avoid causing cascading
errors and poor initialization in other components. Initial errors from
config load cause the initializer to pause and hold requests. Return
typed errors to better communicate failures to clients.
Add code to handle two specific cases - admin wants to bypass
initialization defaulting, and mirror pods (which want to bypass
initialization because the kubelet owns their lifecycle).
Automatic merge from submit-queue (batch tested with PRs 46239, 46627, 46346, 46388, 46524)
Dynamic webhook admission control plugin
Unit tests pass.
Needs plumbing:
* [ ] service resolver (depends on @wfender PR)
* [x] client cert (depends on ????)
* [ ] hook source (depends on @caesarxuchao PR)
Also at least one thing will need to be renamed after Chao's PR merges.
```release-note
Allow remote admission controllers to be dynamically added and removed by administrators. External admission controllers make an HTTP POST containing details of the requested action which the service can approve or reject.
```
