Create trigger before / create trigger block

The original sqlalchemy query still, breaks. And we're not in line with any of the other databases, so far as I can tell (nothing uses `BEGIN ATOMIC`), but we match the spec. And if you do a multiple statement trigger the client sends along less than it should, so you can't actually do a multiple statement trigger in fdbsqlcli. But if you write a query with one action in the trigger it will throw:

    ERROR: Unsupported SQL: CREATE TRIGGER : **UNKNOWN(143)**

Which, I guess still needs some cleanup, but that's closer.