linux: Get the color scheme through xdg-desktop-portal (#11926)

The method has been tested on:
- Gnome 46 (Working)
- Gnome 40 (Not supported)

Tasks

- [x] Implements a draft which get and provides the user theme to
components which needs it
- [x] Implements a way to call the callback function when the theme is
updated
- [X] Cleans the code

Release notes:
- N/A