feat(runtime): refactor function engine

[skyoct]

1. 支持导入模块缓存
2. 将拦截和函数合并到一起执行, 兼容原拦截器写法 并且支持如下写法:

import cloud from '@lafjs/cloud'

export default async function (ctx: FunctionContext, next) {
  let res = null
  try {
    res = await next(ctx)
  } catch(e) {
    return {
      code: 400,
      message: e.message
    }
  }
  return {
    code: 200,
    data: res
  }
}

3. 重新梳理代码逻辑，去除重复代码

[sweep-ai]

Apply Sweep Rules to your PR?

• Apply: Leftover TODOs in the code should be handled.
• Apply: All new business logic should have corresponding unit tests in the tests/ directory.
• Apply: Any clearly inefficient or repeated code should be optimized or refactored.

[skyoct]

@0fatal merge了一下main分支，本pr改动只有runtime