There was an issue where we were backing up group receipts and attachments
that were for expiring messages (which are already excluded from the backup).
This commit excludes these items from the backup, and for backups made
before this change, this commit also deletes these invalid entries at
the end of the restore process.
We also do a little database migration to cleanup any bad state that may
have been imported in the past.
Previously, SQLCipher's memory usage would grow indefinitely, up until
it hit the end of the cursor. We've now switched to a release where the
memory used by the cursor can be bounded.
The "contact" option in the attachments tray now brings you through an
optimized contact sharing flow, allowing you to select specific fields
to share. The contact is then presented as a special message type,
allowing you to interact with the card to add the contact to your system
contacts, invite them to signal, initiate a signal message, etc.
