This fixes the following appstream warning and make program show up in the appstream
data set:
asv-desktop-app-launchable-missing
This `desktop-application` component is missing a `desktop-id`
launchable tag. This means that this application can not be launched
and has no association with its desktop-entry file. It also means no
icon data or category information from the desktop-entry file will
be available, which will result in this application being ignored
entirely.
Part of Debian FreeCAD edition since 2023.
This fixes thumbnailing for XDG desktops. The new script doesn't depend on GNOME libs and works either with python3 or python2.
Also, a thumbnailer config file is added to the installation in CMakeList.txt
Refer to `https://reproducible-builds.org/docs/source-date-epoch/`:
"SOURCE_DATE_EPOCH is a standardised environment variable that
distributions can set centrally and have build tools consume this in
order to produce reproducible output."
