We need to add the pinned_count column to SQLite threads table, so when we (in the next diff) try to store pinnedCount in ThreadInfos, the ClientDB will have the pinned_count for the redux persist migration.
I'm unsure if we should need to run a migration if the column is included in the schema for two reasons:
1. It looks like the SQLite database gets deleted on account log out / re-install
2. I don't think SQLite supports `ADD COLUMN IF NOT EXISTS` so we end up failing the migration if we just try to `ALTER TABLE threads`
a. Maybe the alternative is to not include `pinned_count` in the schema and just run a migration to include it?
Part of https://linear.app/comm/issue/ENG-3396/store-the-number-of-pinned-messages-in-threadinfo
Depends on D7199