style: add @select-item-selected-color

[xrkffgg]

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[中文版模板 / Chinese template]

This is a ...

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

What's the background?

close #2458

Changelog description (Optional if not new feature)

-	Changelog
EN	Add @select-item-select-color to control the color when Select item is selected.
CN	增加 @select-item-selected-color 以控制 Select 选项选中时的颜色。

Self Check before Merge

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

Additional Plan? (Optional if not new feature)

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[github-actions]

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