This is required for the app to appear properly in GNOME Software. https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1081
Another small step towards making the extensions app code self-contained ... https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1081
As we will eventually move the code to a subproject, start arranging it like a top-level srcdir. https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1081