After the "data sync" function adds the MigratingTenantAccessBlocker to MigratingTenantAccessBlockerByPrefix, it should update the donor's state machine doc's "state" to "blocking".

For now, the update can be done using DBDirectClient, see example.

(SERVER-49180 will modify the update so that it is done at a reserved OpTime and also sets "blockTimestamp" to the reserved OpTime's Timestamp.)

Add a jstest that calling donorStartMigration causes the state machine doc's "state" to get updated to "blocking."