Allow the reducer to return operations.

https://linear.app/comm/issue/ENG-10331/modify-the-reducer-to-support-the-db-operations

Depends on D14452

Tested the whole stack on both native and web:

1. Run the app on Redux version 86 with a modification to processDMOperation making all the INBOUND messages unsupported
2. On one platform created a thread and sent a text message. These were visible on the sender, and invisible on the recipient
3. Closed the recipient and added a migration that unshimms the thread creation operations, e.g.

unshimDMOperations(
  state,
  dmOperationTypes.CREATE_THREAD,
  handleReduxMigrationFailure,
): MigrationFunction<WebNavInfo, AppState>),

4. Run the recipient and noticed the thread appearing
5. Added another migration, this time unshimming text messages
6. Run the recipient and noticed messages appearing