DRILL-5116: Enable generated code debugging in each Drill operator
DRILL-5052 added the ability to debug generated code. The reviewer suggested
permitting the technique to be used for all Drill operators. This PR provides
the required fixes. Most were small changes, others dealt with the rather
clever way that the existing byte-code merge converted static nested classes
to non-static inner classes, with the way that constructors were inserted
at the byte-code level and so on. See the JIRA for the details.
This code passed the unit tests twice: once with the traditional byte-code
manipulations, a second time using "plain-old Java" code compilation.
Plain-old Java is turned off by default, but can be turned on for all
operators with a single config change: see the JIRA for info. Consider
the plain-old Java option to be experimental: very handy for debugging,
perhaps not quite tested enough for production use.
close apache/drill#716
