## Back button to navigate out of add-member area
Currently on mobile, once you're in the member area, there is no easy to return to the general settings area, except exiting the settings altogether, which isn't very user friendly. A go-back link solves the problem.
## Styling tweaks
* Removed the background from the leave button
* Added more spacing between the sections on desktop and removed the fixed height for rows
Co-authored-by: Joffrey JAFFEUX <j.jaffeux@gmail.com>
Group channels will allow users to create channels with a name and invite people. It's possible to add people even after creation of the channel. Removing users is not yet possible but will be added in the near future.
Technically a group channel is `direct_message_channel` with a group attribute set to true on its direct message (chatable). This model might evolve in the future but offers much flexibility for now without having to rely on a complex migration.
The commit essentially consists of:
- a migration to set existing direct message channels with more than 2 users to a group
- a new message creator which allows to search, add members, and create groups
- a new `AddUsersToChannel` service
- a modified `SearchChatable` service
