AutoTest: Refactor output handling

Handle getting output from application's process inside base class
and just process output inside the sub classes.
Additionally this is a preparation for being able to process output
for debugging tests as well.

Change-Id: I8a2289dc7faab25afe08530b5021a0318f3ba6a6
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/autotest/testoutputreader.h

@@ -43,8 +43,8 @@ public:
                      QProcess *testApplication, const QString &buildDirectory);
 
 protected:
-    virtual void processOutput() = 0;
-    virtual void processStdError();
+    virtual void processOutput(const QByteArray &outputLine) = 0;
+    virtual void processStdError(const QByteArray &output);
     QFutureInterface<TestResultPtr> m_futureInterface;
     QProcess *m_testApplication;  // not owned
     QString m_buildDir;