improve webhook setup

[rambohe-ch]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line: /kind bug /kind documentation /kind enhancement /kind good-first-issue /kind feature /kind question /kind design /sig ai /sig iot /sig network /sig storage

/kind enhancement

What this PR does / why we need it:

Extract a new function named RegisterWebhook for setting up all webhooks. include controller webhook and independent webhook.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

other Note

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 56.23%. Comparing base (3713163) to head (63147d2). Report is 6 commits behind head on master.

Files	Patch %	Lines
...loymentrender/v1alpha1/deploymentrender_handler.go	0.00%	1 Missing :warning:
pkg/yurtmanager/webhook/node/v1/node_handler.go	0.00%	1 Missing :warning:
...nager/webhook/nodepool/v1beta1/nodepool_handler.go	0.00%	1 Missing :warning:
...kg/yurtmanager/webhook/pod/v1alpha1/pod_handler.go	0.00%	1 Missing :warning:
...r/webhook/yurtappset/v1beta1/yurtappset_handler.go	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2079 +/- ## ========================================== + Coverage 56.09% 56.23% +0.14% ========================================== Files 186 186 Lines 18092 18046 -46 ========================================== Hits 10149 10149 + Misses 6910 6865 -45 + Partials 1033 1032 -1 ``` | [Flag](https://app.codecov.io/gh/openyurtio/openyurt/pull/2079/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openyurtio) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/openyurtio/openyurt/pull/2079/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openyurtio) | `56.23% <0.00%> (+0.14%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openyurtio#carryforward-flags-in-the-pull-request-comment) to find out more.

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[zyjhtangtang]

/LGTM