feat(menu): sub-menu在非弹出模式下同样支持 selectable 属性。

[heyingliang]

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Types of changes

• [ ] New feature
• [ ] Bug fix
• [x] Enhancement
• [ ] Component style change
• [ ] Typescript definition change
• [ ] Documentation change
• [ ] Coding style change
• [ ] Refactoring
• [ ] Test cases
• [ ] Continuous integration
• [ ] Breaking change
• [ ] Others

Background and context

Solution

How is the change tested?

Changelog

Component	Changelog(CN)	Changelog(EN)	Related issues
Menu	sub-menu 在非弹出模式下同样支持 selectable 属性。	sub-menu also supports selectable property in non-popup mode.	#3320

Checklist:

• [ ] Test suite passes (npm run test)
• [ ] Provide changelog for relevant changes (e.g. bug fixes and new features) if applicable.
• [ ] Changes are submitted to the appropriate branch (e.g. features should be submitted to feature branch and others should be submitted to main branch)

Other information