When we allow users to choose between different templates, we should
provide some context for each template to facilitate that choice.
Add that metadata in the form of a .desktop file, which allows us to
specify name and description, and is well supported by our translation
infrastructure.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/812
The gnome-extensions tool code is really independent from the rest of the
code base, and could be used either as part of the gnome-shell build or as
stand-alone project (for example for the extension-ci docker image).
We can actually support both cases by moving the code to a subproject.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/877