Flatpak packaging and Flathub release

[almereyda]

Is your feature request related to a problem? Please describe.

A distribution channel for up-to-date software that works across all distributions, similar to AppImage, is Flathub. It distributes applications for the Flatpak application runtime. It is used for many applications that receive regular updates, and integrates well into CI pipelines. Examples at @flathub exist.

mdSilo Desktop is currently not found there nor on https://flathub.org/apps/search/mdsilo

Describe the solution you'd like

There is a repository in @flathub for automatically building and publishing the mdSilo Desktop app to Flathub.

Describe alternatives you've considered

AppImageLauncher or appimaged should be installed by default by all upstream distributions, to have easy AppImage support by default.

Snap is another alternative to both, which has some friends, but due to its design with a stateful daemon, should not require our attention any further.

RPM packages are used by some well-known distributions, and should be possible to build in a similar way as the DEB packages.

Additional context

This is a beautiful writing environment, and it would be a pity not seeing it available.

[johnblommers]

I would certainly agree that distributing mdSilo via Flathub would be optimal. As a user of topgrade this lets me automatically update all Flathub-installed applications as they release.