perf(useAsyncEffect): move isAsyncGenerator outside the hook

[bijinfeng]

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
• Bug fix
• Site / documentation update
• Demo update
• TypeScript definition update
• Bundle size optimization
• Performance optimization
• Enhancement feature
• Internationalization
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Other (about what?)

💡 Background and solution

isAsyncGenerator 是个纯函数，没必要放在 hook 内部

📝 Changelog

Language	Changelog
🇺🇸 English	move isAsyncGenerator outside the hook
🇨🇳 Chinese	将 isAsyncGenerator 从 hook 内部移到外面

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• 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

[CLAassistant]

All committers have signed the CLA.