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/itestframework.h

@@ -62,6 +62,8 @@ public:
 
     Core::Id settingsId() const;
 
+    Core::Id id() const { return Core::Id(Constants::FRAMEWORK_PREFIX).withSuffix(name()); }
+
     bool active() const { return m_active; }
     void setActive(bool active) { m_active = active; }
     bool grouping() const { return m_grouping; }