Update deps; better window decorations

Update wgpu, resvg, num_enum. Only minor changes to code required.

Update to winit = 0.29.0-beta.0. This has the keyboard-input reform; testing on Wayland seems fine.

Improve toolkit-provided window decorations:

Fix minimise/maximise buttons (typo)
Add borders with drag-resize support (requires Winit 0.29 on Wayland, otherwise appears to support X11 and maybe Windows soon).
Increase size slightly.

kas-gui / kas