Make Direct based on JDBC types not AkTypes

The underlying API that it uses is our embedded JDBC driver, so this actually makes things simpler.

To achieve this, add a method on TClass to return the corresponding java.sql.Types field. This is another small piece of the types translation cleanup.

The YAML test for direct had some cases commented out, most of which would pass now. The remaining one required a fix to embedded JDBC getTime because of MySQL-compatible CAST of TIME to TIMESTAMP.