libportal Implementation v1.0.1

v1.0.1 libportal Implementaion [02-02-2022]

Added

• libportal-0.5 based screenshot backend.

Changed

• io.elementary.Platform version bumped to 6.1 [for elementary OS].
• DesktopFile category to "Graphics;Scanning;".

Removed

• ScreenShot.vala, ScreenShotProxy.vala.
• Gnome Shell screenshot.
• Flatpak home permission.
• Flatpak xdg-pictures permission.
• Flatpak talk to gnome-shell-dbus permission.