Renamed the 'Legacy' classes to have their library prefix (avoid confusion)
Removed the legacy Objective C Thread code (pulled only the NSCoding stuff into the 'SMKLegacy' type)
Refactored the SignalApp class to Swift
Fixed a horizontal alignment issue in the ConversationTitleView
Fixed an issue where expiration timer update messages weren't migrated or rendering correctly
Fixed an issue where expiring messages weren't migrated correctly
Fixed an issue where closed groups which had been left were causing migration failures (due to data incorrectly being assumed to be required)
Shifted the Legacy Attachment types into the 'SMKLegacy' namespace
Moved all of the NSCoding logic for the TSMessage
Changed the min OS version to iOS 13.0 (support for 'Identifiable')
Removed the alternate approaches to fetching the userKeyPair and userPublicKeyHexString (no consistently routed through the caching method)
Migrated the 'OWSIdentityManager' logic to use the new 'Identity' type
Added the 'Setting' table and got the pattern working fairly nicely (unfortunately there isn't a good way to avoid key collision without proper enums)
Updated the SessionSnodeKit to migration it's data from YDB to GRDB
Updated the SessionSnodeKit to use GRDB throughout it's logic
Setup a migration pattern
Setup the database configuration and security
Started defining the database schema
Started working on the migrations for SessionSnodeKit