Uninstall confirmation - ask whether to clear app storage for Flatpaks

Submitted by Allan Day @aday

Link to original bug (#789770)

Description

Created attachment 362759 mockup

One of the nice things about Flatpak is that each app has its storage in a single location, which makes managing app data a lot easier. When you uninstall a Flatpak, it would be good if users could have the option whether to clear its data, in order to save themselves some space.

See the attached mockup for how this could be done.

Attachment 362759, "mockup":