Experiment with navigation buttons in message views

[alya]

We should experiment with showing navigation buttons in message views. This would make it easier to navigate from those views, but also has potential down sides, as discussed at #mobile-team > UI redesign: root level nav @ 💬.

References

• The user need which this is a possible solution to: #1120

[alya]

Also discussed at #mobile > bottom nav bar on combined feed.