feat: optimize useRequest data return type of typescript #237

[XiaoDaiGua-Ray]

[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?)

🔗 Related issue link

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English
🇨🇳 Chinese	y

优化返回 data 值的类型推导，现在满足以下的原则：

1. 如果配置了 initialData，未配置 formatResult，data 类型则为 service 方法的返回值，不联合 undefined 类型
2. 如果配置了 formatResult，未配置 initialData，data 类型则为 formatResult 的返回值类型，data 会联合 undefined 类型
3. 如果同时配置了 initialData, formatResult，那么 data 的值以 formatResult 的返回值类型为准，并且 data 会联合 undefined 类型

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• Follow our Code of Conduct
• Read the Contributing Guidelines
• Read the docs
• 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