Harden DELETE/UPDATE trigger edge cases and expand test coverage

[Copilot]

CREATE TRIGGER CALL already passed row data for basic INSERT/UPDATE/DELETE cases, but DELETE ignored prevent/INSTEAD OF outcomes and AFTER UPDATE passed the new row twice.

Changes

• DELETE: Honor table.delete() === false for BEFORE prevent and INSTEAD OF so matching rows stay in the table and skip AFTER DELETE / OUTPUT
• INSTEAD OF DELETE: Return false from table.delete so callers treat it like a prevented delete
• AFTER UPDATE: Capture the pre-update row and pass (oldRow, newRow) to triggers
• Tests: Extend test/test1119.js for AFTER UPDATE, prevent-delete, and INSTEAD OF DELETE

alasql.fn.onUpdate = function (oldRow, newRow) {
  // oldRow.a === 10, newRow.a === 20
};
alasql('CREATE TRIGGER t AFTER UPDATE ON six CALL onUpdate()');
alasql('UPDATE six SET a = 20 WHERE a = 10');

alasql.fn.block = function () { return false; };
alasql('CREATE TRIGGER t2 BEFORE DELETE ON seven CALL block()');
alasql('DELETE FROM seven WHERE a = 1'); // row kept

• Fixes Triggers - Database Event Automation Support #2365