Add support for the Dynamic Launcher portal

[ignapk]

Description

This adds support for the xdg-desktop-portal dynamic launcher portal, that will allow to install desktop files without the need for manually giving permission with a command or Flatseal. Upon clicking the Add Desktop Entry option of a wine installed application, the portal will open a dialog where the user can see the app icon, can change the name and confirm or cancel.

Screenshots:

What's missing:

• Support for [Desktop Action Configure] group in the .desktop file, currently the portal requires exactly one group in the .desktop file for security reasons
• Requiring xdg-desktop-portal version >= 1.20.1, otherwise doesn't work due to Cannot create/ install dynamic launchers flatpak/xdg-desktop-portal#1674
• Rework to delay showing the toast

Fixes #1366

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Unfortunately, I only managed to test installing the desktop file itself, as I get an error when trying to run apps from the desktop files on main as well:

(process:2): GLib-GIO-ERROR **: 15:52:04.166: Settings schema 'com.usebottles.bottles.Devel' is not installed

But the created desktop files are otherwise almost identical to the ones from main (bar the configure action) and show up in the app grid just fine \o/