Free-naming of confirmed GW's

Allows naming of confirmed GW superevents to the GWYYMMDDA format or a user specified name. This was implemented on catalog-dev, see #214 (closed) for details.

When a superevent is confirmed as a GW, a GW ID is assigned and a second URL is created:

https://gracedb-dev2.ligo.org/superevents/S220315c/view/ is the same s event as https://gracedb-dev2.ligo.org/superevents/GW220315A/view/

This MR should be approved along with client!71 (merged).