Create bridge for custom UDFs to operate in vectorized mode

Suppose you have a custom UDF myUDF() that you've created to extend hive. The goal of this JIRA is to create a facility where if you run a query that uses myUDF() in an expression, the query will run in vectorized mode.

This would be a general-purpose bridge for custom UDFs that users add to Hive. It would work with existing UDFs.

I'm considering a separate JIRA for a new kind of custom UDF implementation that is vectorized from the beginning, to optimize performance. That is not covered by this JIRA.