Stop using the parser TypeComputer

As it has different views about the type system than the SQL Layer.

AISTypeComputer now just hooks up types for columns, propagates subquery result columns, attaches collate clauses and marks non-expression subqueries as returning boolean (last is assumed to happen by ConstantFolder).

The rule's test changes are all just removing casts that use to be added by the TypeComputer. Later rules generally do the same thing e.g. for conditionals. More divergent behavior happens with functions, such as COALESCE showing the type picking behavior *actually* implemented by OverloadResolver.