DRILL-6381: Address code review comments (part 3).
DRILL-6381: Add missing joinControl logic for INTERSECT_DISTINCT.
- Modified HashJoin's probe phase to process INTERSECT_DISTINCT.
- NOTE: For build phase, the functionality will be same as for SemiJoin when it is added later.
DRILL-6381: Address code review comment for intersect_distinct.
DRILL-6381: Rebase on latest master and fix compilation issues.
DRILL-6381: Generate protobuf files for C++ native client.
DRILL-6381: Use shaded Guava classes. Add more comments and Javadoc.
