AutoTest: Provide easy Id<->ITestFramework * mapping

They are 1:1, idea is to replace (most of the) Id uses with the
framework itself, overall simplifying e.g. TestFrameworkManager.

For a salami-tactics transition, easy convervion between the two helps.

Change-Id: Ib6d166ae34a3189d900353be7a181a1e45467a7c
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/autotest/testframeworkmanager.h

@@ -54,6 +54,9 @@ class TestFrameworkManager
 public:
     static TestFrameworkManager *instance();
     virtual ~TestFrameworkManager();
+
+    static ITestFramework *frameworkForId(Core::Id frameworkId);
+
     bool registerTestFramework(ITestFramework *framework);
 
     void activateFrameworksFromSettings(const Internal::TestSettings *settings);