Nowadays we can set up translations automatically, but only when
the domain is provided with the metadata.
This can be a problem, for example our extension templates use
the automatic translation handling that we recommend, but as a
result the code will throw an error unless `gettext-domain` is
added to the metadata.
Binding a text domain is cheap enough to not care about unnecessary
or duplicated calls, so add a final fallback to the UUID when no
domain was provided as parameter or in the metadata.
There is already a precedent with the `gnome-extensions pack` command
that falls back to the UUID when no explicit gettext domain was
included in the metadata.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2888>
a6d8e7ab6f