Let the users wake up the event loop and then they could poll their
user sources.
Co-authored-by: Mads Marquart <mads@marquart.dk>
Co-authored-by: daxpedda <daxpedda@gmail.com>
Add a simple `ApplicationHandler` trait since winit is moving towards
trait based API. Add `run_app` group of APIs to accept `&mut impl
ApplicationHandler` deprecating the old `run` APIs.
Part-of: https://github.com/rust-windowing/winit/issues/3432
