AutoTest: Allow colored commandline output

Some test frameworks allow to print their output colorful
to further indicate meanings of messages or test results.
Provide a highlighter for the textual output of the results
and enable this functionality for GTest and Boost UTF.
Keep at least a small backdoor for overwriting this by
the user.

Fixes: QTCREATORBUG-22297
Change-Id: Iddd2b734416de807635d90c6519553081f7372f2
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/autotest/autotestconstants.h

@@ -59,4 +59,7 @@ enum class TestRunMode
     DebugWithoutDeploy,
     RunAfterBuild
 };
+
+enum class OutputChannel { StdOut, StdErr };
+
 } // namespace Autotest