AppImage works by decompressing the "program" in a temporary directory.
So the executable path is not the path of the AppImage file.
By using the environment variables set by appimage we can find the correct
"path" of the executable.
Fixkiwix/kiwix-desktop#46
The `common` name is from the time where kiwix was only one repository
for all the project (android, desktop, server...).
Now we have split the repositories and kiwix-lib is the "common" repo,
the "common" directory is somehow nonsense.