[SQLite] Add a new column to outbound_p2p_messages table

Summary:
Add a field that marks messages as being subjects to automatic retries.

https://linear.app/comm/issue/ENG-8729/automatic-retries-for-non-composable-dms

Test Plan: Open an existing app and check if the migration doesn't throw. Start a fresh app and check if the DB creation succeeds. Further testing is performed later in the stack.

Reviewers: kamil, marcin

Reviewed By: kamil

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D12742