Try `egui_glow` with `egui-winit` on web

[emilk]

It would be great if we could get egui-winit to work on the web using egui_glow for rendering. If that worked, we could potentially make eframe just a thin wrapper around those two crates, with no need for egui_web.

Related: #685 by @AlexApps99 and #868 by @t18b219k. Also related: #1022

Tracking issues (from #1022 (comment)):

• scan_code and virtual_key_code are swapped rust-windowing/winit#2092
• Tracking Issue: Implement DeviceEvent::ModifiersChanged rust-windowing/winit#1151

[KentaTheBugMaker]

I'm working for it.
and found EventLoopProxy on wasm does not implement Send trait .
so we need to some treat for it.

[KentaTheBugMaker]

progress .
copy NeedRepaint from web and ignore repaint when repaint signal emitted on web .
works but crash.

[KentaTheBugMaker]

crash caused from wasm std::thread.
so disable sleep in wasm.

[KentaTheBugMaker]

sleep disabled works perfect on my laptop but still need to port persistence.

[KentaTheBugMaker]

update
We need to disable browser's context menu for canvas.

[KentaTheBugMaker]

I will make draft PR.