feat(menu): add MenuItemGroupProps export

[yoyo837]

🤔 This is a ...

• New feature
• Bug fix
• Site / document update
• Component style update
• TypeScript definition update
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Other (about what?)

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💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English
🇨🇳 Chinese	添加类型导出

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• Demo is updated/provided or not needed
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[codecov]

Codecov Report

Merging #21356 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #21356   +/-   ##
=======================================
  Coverage   97.55%   97.55%           
=======================================
  Files         300      300           
  Lines        7003     7003           
  Branches     1931     1884   -47     
=======================================
  Hits         6832     6832           
  Misses        171      171

Impacted Files	Coverage Δ
components/menu/index.tsx	99.13% <ø> (ø)	⬆️

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