Global Shortcuts portal support

[eternal-sorrow]

Add support for Wayland with Global Shortcuts portal. Documentation is here: https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.GlobalShortcuts.html

[TingPing]

This project isn't really active, I'd recommend looking towards libportal for this feature: flatpak/libportal#134

[eternal-sorrow]

As a developer, I would use libportal of course. But as a user of some apps that already use keybinder, I would love for those apps to support global shortcuts on wayland.

[KarolBedkowski]

According to https://wiki.archlinux.org/title/XDG_Desktop_Portal and my finds Global Shourcuts is not very well adopted jet.
But any PR-s will be welcome.