HHH-15443 Allow JdbcType to wrap read and write expressions

[beikov]

https://hibernate.atlassian.net/browse/HHH-15443

[gavinking]

I'm not sure I like what's going on here, but that could just be because I don't understand it. Could we talk it over sometime?

[gavinking]

OK, so after discussing offline, my suggestion is that it would be better if this worked by having the Type double-dispatch back to the Dialect, and let the Dialect render the SQL.

The justification for this is: the generated SQL in principle depends on both the Type and the Dialect, and the SQL syntax in principle is a responsibility of the dialect.