DRILL-5257: Run-time control of query profiles
Adds a run-time option to save (default) or not save query profiles.
Adds a run-time option to save query profiles in "debug" mode:
that is, after returning the last client response. (Normal mode is
to return the response before writing the profile.)
Tests for normal case are normal unit tests. Tests for debug mode
case are unit tests using the new framework that parse profiles.
The test framework is extended to save query profiles using this
new option.
Modifies the test framework to use the new options when a test
asks to save query profiles.
closes #747
