Add per-group nicknames

[Powsu]

Describe your feature proposal
Similar to discord, which allows users to have per-server profiles, add the ability to have per-group nicknames

Is your feature request related to a problem? Please describe.
When a nickname reservation error occurs, or the user chooses to within the group chat settings, prompt for an alternative nickname. This nickname should only apply to the individual group room

Additional context
The purpose of this feature request is to suggest a potential resolution/fix to #238