[migration] set a cnxset before process_script()
Not pretty, but I don't have a better idea right now and this at least
ensures migration scripts get run in the expected environment and can
access sql stuff as before.
sync_schema_props_perms(('State', 'state_of', 'Workflow'), commit=False)
sync_schema_props_perms(('State', 'name', 'String'))