Added some new properties to the OpenGroupV2
Moved a number of methods and variables from OpenGroupAPI to OpenGroupManager (anything doing actual logic)
Moved the message signing into the OpenGroupAPI (since that's the only place it happens)
Renamed remaining old model classes to start with 'Legacy' to make clean up easier
Updated the OpenGroupAPI poll method to use the same logic as it previously did to determine if it should retrieve recent messages or messages since the last one
Split the OpenGroupAPIV2 into separate files
Started working on the new auth and blinded-id approaches (new auth working with un-blinded id suggesting blinded-id code is incorrect)
Updated the SOGS request/response types to use Codable
Updated the SOGS Request type to use enums instead of strings for keys (to reduce likelihood of typos breaking things)
Updated SessionMessagingKit to use Codable and JSONEncoder/JSONDecoder instead of the legacy JSONSerialization
Cleaned up some naming conventions in the SessionMessagingKit (calling a URLRequest body 'parameters' is very confusing...)
Removed the custom TSRequest class (just using standard URLRequest everywhere instead)
Added a number of extension functions to enable some more functional-coding styles
Added extensions to Sodium methods to allow scalar multiplication and the ability to hash providing a salt and a personalisation value (both needed for new SOGS auth)
Fixed an issue where the legacy auth for SOGS could crash due to threading issues (multiple threads accessing the same variable)
Fixed an issue where if you were in two rooms in a single SOGS and deleted one of them, the other room would stop getting updates as the server public key was getting removed
Added the MessageRequestsViewController
Added a 'Message Requests' button to the settings screen
Added accept/reject buttons for message requests to the ConversationVC
Added the ability to hide the message request item on the HomeVC (re-appears if you get a new message request)
Added code to handle an edge-case where the message request approval state wouldn't be returned to the sender due to the recipient running an old version of the app
Prevented contacts which aren't associated with an approved thread from appearing when creating a closed group
Disabled notifications for threads which aren't approved
Updated the app notification count to exclude unapproved messages
Updated the app to ignore closed group creation messages if the group has no admins which are approved contacts
Fixed up the keyboard avoidance behaviour in the ConversationVC
Fixed a couple of minor interaction issues which affected some devices
Fixed an issue where the database migrations would run on the 2nd launch when creating a new account (causing odd behaviours)
Updated the share extension to load URL previews.
Updated the ThreadPickerVC to send plain text & URLs in the same way they are sent for normal messages.
