Restructure GUI

[frostworx]

This is mainly a meta issue, to gather all construction sites in one play.

I started to restructure the whole GUI to make it more versatile.
Planned core features are at least (no special order, list might be incomplete, some could be dropped)

• Navigation in between the different menu settings
• Favorites Menu - Favorites Menu #148
• Favorite Menu Entry Checkbox Selector
• Several settings levels, similar to "KODI" - Settings Levels #149
• Remove tabs to be "wayland" compatible - Settings Menu Tabs don't work under wayland #118
• Dropdown selection for the default GUI to be opened after the timeout requester
  (Editor, Favorites, Game, GameTemplate, Global, Menu, Vortex, more(?)) (some just don't make any sense as default)
• Sort (all menus) by Category
• Blocklist Categories
• ?

[frostworx]

yay - added in https://github.com/frostworx/steamtinkerlaunch/releases/tag/v3.1.335