[SQLLogicTest] Expected error message is no longer optional for statement error

[Tishj]

Previously this was accepted:

statement error
select non_existant_function();

Now this will fail to parse:

/Users/thijs/DuckDBLabs/duckdb/test/sqlite/sqllogic_parser.cpp:115: FAILED:
explicitly with message:
  test/tmp/tmp.test:3: Failed to parse statement: statement error needs to have
  an expected error message

Instead the minimal syntax for a statement error is:

statement error
select non_existant_function();
----

The hope is that this will encourage all statement errors going forward to provide an expected error message in addition to the now required ---- and to incrementally fix old statement error statements by adding a proper expected error message pattern.

[Mytherin]

Thanks! I think this will break the SQLLogicTests and some extensions (and perhaps more) - but let's just get this in now and fix those after.