improve nodepool conversion

[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:

Compare to v1alpha1.NodePool, A new field named spec.HostNetwork is added in v1beta1.NodePool. In order to keep consistency for NodePool resource, we add nodepool.openyurt.io/hostnetwork annotation for v1alpha1.NodePool to support hostNetwork NodePool feature.

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

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 56.21%. Comparing base (3713163) to head (ef6ae46). Report is 7 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2080 +/- ## ========================================== + Coverage 56.09% 56.21% +0.11% ========================================== Files 186 186 Lines 18092 18046 -46 ========================================== - Hits 10149 10144 -5 + Misses 6910 6869 -41 Partials 1033 1033 ``` | [Flag](https://app.codecov.io/gh/openyurtio/openyurt/pull/2080/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/2080/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openyurtio) | `56.21% <ø> (+0.11%)` | :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