demos/plplay: Keybinds to toggle UI and fullscreen
Currently for the demo plplay there is no way to fully hide the UI at runtime, so there is a new keybind added to toggle the UI. There is also a keybind to toggle fullscreen.
It's convenient to hide the UI when taking screenshots of the whole window or when trying to examine the output closely.
Keybids:
- H - Hide UI
- F - Fullscreen toggle