Permalinks in thread message feed

There are 2 types of permalinks:

• parent message permalink
  • needs to generate a normal permalink
  • the current permalink generation uses context.troupe() but that's not going to be enough when the parent message is not from the room shown in the main message feed (we don't allow TMF from any other room than context.troupe())
• child message permalink
  • solution for this will need more investigation
  • the current high-level view https://gitlab.com/gitlab-org/gitter/webapp/issues/741#table-comparing-the-different-implementation-of-operations-on-messages