fix(OverflowPopover): make OverflowPopoverContext to a single to issue on multiple instances (#5738)

[Jianrong-Yu]

This PR fixes #5738 by make the context OverflowPopoverContext to a singleton, to make it works for multiple UI5 instanced introduced by UI5 scoping. The singleton solution is copied from packages/base/src/context/StyleContext.ts:

const SYMBOL = Symbol.for('@ui5/webcomponents-react/StyleContext');
//...
export function getStyleContext(): typeof StyleContext {
  globalThis[SYMBOL] ??= StyleContext;
  return globalThis[SYMBOL];
}

Before:

After:

Pull Request Checklist

• Reviewed the Contributing Guidelines
  • Especially the How to Contribute section
• Correct commit message style

[coveralls]

Pull Request Test Coverage Report for Build 8837819142

Details

• 8 of 8 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.009%) to 88.484%

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Totals
Change from base Build 8834380725:	0.009%
Covered Lines:	5417
Relevant Lines:	6122

---

💛 - Coveralls

[Lukas742]

Hi @Jianrong-Yu

thanks for creating this PR! Unfortunately I don't know when I'll get around to looking at it in depth, but your contribution is much appreciated :)

[Lukas742]

LGTM 🚢

Thank you!

[ui5-webcomponents-react-bot]

🎉 This PR is included in version v1.28.1 🎉

The release is available on v1.28.1

Your semantic-release bot 📦🚀