While we can now build gnome-extensions-tool as stand-alone project,
we are currently missing any translations, as those are part of
gnome-shell.
The easiest option for addressing this would be to symlink the toplevel
po directory into the subproject, however that would mean duplicating
the entire gnome-shell message catalogs.
So instead, set up a bare po directory and provide a script to populate
it from the translations in the toplevel po directory.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/877
