***What?** Implement introduction between owner's contact and their mailbox.
1) Design introduction protocol based on remote contact to contact introduction (and current implementation)
1) Design state machine for introduction based on [#1231](https://code.briarproject.org/briar/briar/issues/1231)
2) Implement BSP client for mailbox introduction.
#### Tasks
* [ ] Discussion
+See [here](https://code.briarproject.org/briar/briar/issues/1231) for upcoming "add remote contacts" feature
+Do we still need SYNC-protocol support or could we implement this only using the Mailbox protocol?
+Error handling: Ensure mailbox/owner contact lists are in sync and recover after failure (Do we need a Mailbox Protocol request to synchronize contact lists?)
