Merge CppTools into CppEditor

There was no proper separation of responsibilities between these
plugins. In particular, CppTools had lots of editor-related
functionality, so it's not clear why it was separated out in the first
place.
In fact, for a lot of code, it seemed quite arbitrary where it was put
(just one example: switchHeaderSource() was in CppTools, wheras
switchDeclarationDefinition() was in CppEditor).
Merging the plugins will enable us to get rid of various convoluted
pseudo-abstractions that were only introduced to keep up the artificial
separation.

Change-Id: Iafc3bce625b4794f6d4aa03df6cddc7f2d26716a
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/autotest/loadprojectscenario.h

@@ -27,7 +27,7 @@
 
 #include <QObject>
 
-namespace CppTools { namespace Tests { class TemporaryCopiedDir; } }
+namespace CppEditor { namespace Tests { class TemporaryCopiedDir; } }
 namespace ProjectExplorer { class Kit; }
 
 namespace Autotest {
@@ -50,7 +50,7 @@ private:
     bool loadProject();
 
     TestTreeModel *m_model = nullptr;
-    CppTools::Tests::TemporaryCopiedDir *m_tmpDir = nullptr;
+    CppEditor::Tests::TemporaryCopiedDir *m_tmpDir = nullptr;
     ProjectExplorer::Kit *m_kit = nullptr;
 };