AutoTest: Clean up header mess

Better decoupling and reduced binary size.

Change-Id: I4f6239979d9d7dae4ad92f19ec8420be38372c07
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/autotest/testnavigationwidget.h

@@ -26,7 +26,6 @@
 #pragma once
 
 #include "itemdatacache.h"
-#include "testrunner.h"
 
 #include <coreplugin/inavigationwidgetfactory.h>
 
@@ -53,6 +52,7 @@ class TestTreeModel;
 
 namespace Internal {
 
+class TestRunner;
 class TestTreeSortFilterModel;
 class TestTreeView;