Redesign Skin of SkinnedMeshRenderer

[GuoLei1990]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• Completely solve the historical design issues of Skin related interfaces, all skin related information is officially migrated to Skin.
• Redesign Skin’s operation logic，performance improve 20%.
• Opt skeleton find performance when load parse glTF.
• Improve the cloning mechanism. For deep cloning, the reference relationship after cloning can be kept unchanged.

Performance Improvements

Before: FPS: 39 Memory: 103M Load: 300ms
Now: FPS: 48(Up 23%) Memory: 97M(Down 6%) Load: 280ms

Case:

Enviroement:

[codecov]

Codecov Report

Attention: Patch coverage is 55.84416% with 68 lines in your changes are missing coverage. Please review.

Project coverage is 66.08%. Comparing base (4b28345) to head (1bdeecc).
Report is 6 commits behind head on main.

❗ Current head 1bdeecc differs from pull request most recent head b44a62a

Please upload reports for the commit b44a62a to get more accurate results.

Files	Patch %	Lines
packages/core/src/mesh/Skin.ts	52.83%	18 Missing and 7 partials ⚠️
packages/core/src/mesh/SkinnedMeshRenderer.ts	66.03%	8 Missing and 10 partials ⚠️
packages/core/src/Entity.ts	40.00%	12 Missing ⚠️
packages/core/src/clone/CloneManager.ts	33.33%	6 Missing and 2 partials ⚠️
packages/loader/src/gltf/parser/GLTFSkinParser.ts	50.00%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2100      +/-   ##
==========================================
- Coverage   66.09%   66.08%   -0.02%     
==========================================
  Files         460      461       +1     
  Lines       23013    23058      +45     
  Branches     3370     3385      +15     
==========================================
+ Hits        15211    15237      +26     
- Misses       6637     6650      +13     
- Partials     1165     1171       +6     

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[zhuxudong]

remove

[GuoLei1990]

done