[Concurrency] Asynchronous functions

[John_Lin]

@unixzii

This can be implemented by simply wrapping the Task.runDetached method like this:

func asyncWrapper<T>(_ operation: () async -> T, completion: (T) -> Void) {
    let _ = Task.runDetached {
        let result = await operation()
        completion(result)
    }
}

This is useful, look forward to a polished way to do so.

Thanks for great solution,
the public func get() async throws -> Success { ... }
interface make it looks like it requires another await.
Maybe we should have a public func get(completion: (Success)->Void) throws -> Void interface as well.
But that should belongs to the structured concurrency thread.