Move translation-attic to this namespace, and archive the gitolite

The translation-attic repo (https://gitweb.torproject.org/translation-attic.git/ ) should be moved to gitlab, and is better to do it now because we are retiring some of the translations we have in Transifex, and we should send the new url to its stakeholders / mantainers. (i.e. Orfox sunsetting strings).

Once done, we should tell tpa to archive the old repo.