Create user for tor tarball releases on dist

Right now, when c-tor releases, after the reproducible builds are completed, and offline signatures match, the resulting tarball is uploaded by the release engineer (@dgoulet) to dist.tpo. He is currently using his personal account to do this, and we'd like to have a release tarball user who has the same privileges so it doesn't have to be explicitly attached to his user, and can be used to smooth out some of the release engineering.

Perhaps in a similar way that there is a tordeb@palmeri.torproject.org user for uploading to deb.torproject.org there could be a user created (perhaps tortgz would be a sufficient name) that has access to dist.tpo to publish the generated/verified tar.gz to the same locations that the user dgoulet currently has. This user would be used by the release engineer, and just needs similar access on dist for writing to the same locations in order for it to do its work.