This reuses the new common library [1] to mirror a new phabricator repo (e.g [2]).
This:
- creates a new repository in our forge
- clones locally a new repository
- pushes the local clone to the new swh forge repository
- configures the remote properly
An example of mirrored repository bootstraped with this.
Related to T2225
[1] Depends on D7847
[2] https://forge.softwareheritage.org/source/forgerie/