Simple plugin to show player in fullscreen

[toy]

Check-list

• [ ] There is a linked issue discussing the motivations for this feature or bugfix
• [ ] Unit tests have been added where possible
• [ ] I've added / updated documentation for any user-facing features.
• [ ] Performance seems to be comparable or better than current main

What this change is adding / fixing

Simple plugin to switch player to fullscreen mode when enabled.

[declension]

Thanks. I don't think this is something that makes sense as a plugin though (we have too many probably already) - it should be a config option at app level.

[toy]

My impression was that global settings are intentionally small and everything possible should be covered in plugins. Also I don't see a tab in settings fitting for "open in fullscreen" checkmark.