Resolve "Permalinks in thread message feed"

Closes #2218 (closed)

There is one refactoring commit that splits the findChatMessagesInTroupe method into two independent methods 7b2a48fb. It's going to be best to look at this one in isolation because it is not directly related to the permalink feature.

The rest of the MR is implementing addition to permalink functionality: when permalink points to the child message, Gitter will highlight parent message, opens TMF and highlights the child message.

TODO:

• Clicking the timestamp in TMF populates location bar with permalink
• Server uses parent message when aroundId belongs to child message and adds the child message to the response
• Client checks whether the permalinked message is a child message and if yes, it highlights parent, opens TMF, and highlights child
• TMF scrolls to the highlighted child

Testing strategy

1. Generating permalink by clicking on timestamp changes location bar in the browser without reloading the page
   • in MMF
   • in TMF
   • in not logged in MMF
2. Going to MMF permalink works as before (message is highlighted and in the view)
3. Going to TMF permalink highlights parent message in MMF, opens TMF and scrolls to + highlights the child message
4. all highlights disappear after 5s
5. sanity check on fetching messages
   • infinite scrolling works
   • archive view sets the boundaries of a day