This commit add a first version code to build a flatpak of kiwix-desktop.
It is mainly based on the PR #254 of @birros (hence he is the author of this commit)
However there is some differences :
- I (@mgautier) create a new builder to run the flatpak build instead of using a new
dependency.
- Use the flatpak platform to install org.kde.Platform and org.kde.Sdk
This code version doesn't correctly work but I wanted to commit the birros' code
without too many modification (even if there is a lot).
8d58d8d7cb