egui-winit: emit physical key presses when a non-Latin layout is active

[TicClick]

trafficstars

resolves https://github.com/emilk/egui/issues/4081 (see discussion starting from https://github.com/emilk/egui/issues/3653#issuecomment-1962740175 for extra context)

this partly restores event-emitting behaviour to the state before #3649, when shortcuts such as Ctrl + C used to work regardless of the active layout. the difference is that physical keys are only used in case of the logical ones' absence now among the named keys.

while originally I have only limited this to clipboard shortcuts (Ctrl+C/V/X), honestly it felt like a half-assed solution. as a result, I decided to expand this behaviour to all key events to stick to the original logic, in case there are other workflows and hotkeys people rely on or expect to work out of the box. let me know if this is an issue.