Incorrect typeName for CastingExpressions in mysql

[dchung-cargurus]

In our upgrade to ktorm 3.6, we've found an issue related to the typeName being incorrect for mysql when visitCasting runs on CastingExpressions. For example, from https://www.w3schools.com/sql/func_mysql_cast.asp the VarCharSqlType yields a syntax breaking argument for cast.

For instance, the expressiontable.cast(VarCharSqlType) will yield the sql cast( id AS VARCHAR) rather than cast(id AS CHAR), which would be the valid sql expression (https://www.w3schools.com/sql/func_mysql_cast.asp).