feat: new api interfaceSetResponseFileHandler

[jinzhongjia]

No description provided.

[AlbertShown]

I don't know if Zig has async operations, but if you need it this is how it works:

1. Zig set setConfig(asynchronous_response, true) = Means WebUI will wait for xxx_set_response_xxx()
2. WebUI calls a user callback function (Event, FileHandler...)
3. Callback function return right away with empty response (async operation)
4. WebUI detect asynchronous_response is true, so WebUI wait for callback function response...
5. Callback function do some work...
6. Callback function finish, then return a response to Zig
7. Zig calls xxx_set_response_xxx()
8. WebUI sends the response to UI (web browser)
9. Done.

[jinzhongjia]

At present Zig’s Async is frozen and cannot be used

[AlbertShown]

Okay, in the future, when Zig fully implement async, we can add it to the Zig wrapper as WebUI is already fully supporting async.