Proper deployment of swh-graph with debian package

Right now the deployment of swh-graph on granet.i.s.o is a venv in /opt and two systemd config files (/etc/systemd/system/swhgraphdev.service and /etc/systemd/system/swhgraphshm.service).

We should:

• make a debian package of swh-graph
• #3564 (closed): puppetize the systemd files.
• #3564 (closed): add monitoring alert in case the service is not running (check for port or something)

---

Migrated from T3168 (view on Phabricator)