Updated the settings screens to have the "rounded group" styling
Added a "loading conversations" label to the Message Requests screen before the conversations load
Removed the legacy UserCell (replaced with the more reusable 'SessionCell')
Renamed a few things to make them more generic and reusable
Fixed a bug where returning from the background on the conversation screen would result in the input view being hidden
Refactored the PhotoCollectionPickerViewController to use the SettingsTableViewController convention
Updated the SettingsTableViewModel to worked based on Combine instead of the DatabaseObservable so it's more reusable for non-db cases