Show the list of UDFs used in a query in the query profile

When debugging JVM memory issues of impalads, we want to know if there are any Java UDFs contribute to that. It'd be helpful to show the list of UDFs that are used in a query in the query profile.

On the other hand, Java UDFs are usually low performant comparing to native UDFs. We can show a warning in the profile saying Java UDFs are used.

CC michaelsmith