bug: menu accelerators don't trigger on windows

[evanwporter]

Describe the bug
Accelerators like Cmd+S (save) don't trigger on_menu_event

Additional context
This is a Tauri problem as described here.

[andrewbenington]

this could be faked by adding a keyboard event listener to a wrapper DOM element, maybe in App.tsx. we need to make sure the fake event is only triggered on Windows though, probably by checking navigator.agent