Wayland: implement key repeat (zed-industries#8038)

Wayland requires the client to implement key repetition. This PR
implements the functionality as it's supposed to, but I don't see the
`repeat_info` event come in so the feature uses the default values (but
my system is configured for a much smaller `delay` and a much faster
`rate`). But this is good enough for now.

https://wayland-book.com/seat/keyboard.html#key-repeat


[Kooha-2024-02-20-20-42-12.webm](https://github.com/zed-industries/zed/assets/1423607/fb9fc327-efb7-43d1-9b53-1f8a3d9ba608)