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/autotoolsprojectmanager/autotoolsbuildsystem.cpp

@@ -30,7 +30,7 @@
 #include "makefileparserthread.h"
 #include "makestep.h"
 
-#include <cpptools/cppprojectupdater.h>
+#include <cppeditor/cppprojectupdater.h>
 #include <projectexplorer/buildconfiguration.h>
 #include <projectexplorer/target.h>
 #include <qtsupport/qtcppkitinfo.h>
@@ -44,7 +44,7 @@ namespace Internal {
 
 AutotoolsBuildSystem::AutotoolsBuildSystem(Target *target)
     : BuildSystem(target)
-    , m_cppCodeModelUpdater(new CppTools::CppProjectUpdater)
+    , m_cppCodeModelUpdater(new CppEditor::CppProjectUpdater)
 {
     connect(target, &Target::activeBuildConfigurationChanged, this, [this]() { requestParse(); });