Generate a FlatPak manifest from a Cabal package description. Inspired by Richard Szibele's stackpak: https://gitlab.com/rszibele/stackpak#readme See also David Lettier's post on Flatpak for Haskell: https://medium.com/@lettier/how-to-flatpak-a-haskell-app-into-flathub-86ef6d69e94d