RFE: Improve flatpak support

[timlau]

• handling of flatpak remotes
• set active flatpak, if multiple versions is installed (like a prod / beta release)
• show if there is a new beta release to an already install stable release
• open package info on flathub
• support for delete data on uninstall

[timlau]

Add new repository from command line

flatpak remote-add --if-not-exists flathub-beta https://flathub.org/beta-repo/flathub-beta.flatpakrepo

Remove repository from command line

flatpak remote-delete --force flathub-beta

Set active flatpak from command line

flatpak list | rg shotcut
Shotcut org.shotcut.Shotcut     26.1.16       beta    flathub-beta    user
Shotcut org.shotcut.Shotcut     25.12.31      stable  flathub         user

flatpak make-current org.shotcut.Shotcut beta -u

[timlau]

Open Package on flathub

url is
https://flathub.org/en/apps/<flatpak-ref>
ex.
https://flathub.org/en/apps/io.github.nokse22.high-tide

[timlau]

support delete data on uninstall

flatpak uninstall --delete-data <flatpak-ref>