Function createDeferred

createDeferred<T>(): Deferred<T>
创建一个延迟 Promise，可在外部调用其 resolve / reject
Type Parameters
- T
Returns Deferred<T>
包含 promise、resolve、reject 的 Deferred 对象
Example
```
const deferred = createDeferred<string>()
setTimeout(() => deferred.resolve('done'), 1000)
await deferred.promise
```
- Defined in async.ts:69