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/cppcheck/cppchecktool.h

@@ -38,7 +38,7 @@ class FilePath;
 using FilePaths = QList<FilePath>;
 }
 
-namespace CppTools {
+namespace CppEditor {
 class ProjectPart;
 }
 
@@ -75,8 +75,8 @@ public:
 
 private:
     void updateArguments();
-    void addToQueue(const Utils::FilePaths &files, const CppTools::ProjectPart &part);
-    QStringList additionalArguments(const CppTools::ProjectPart &part) const;
+    void addToQueue(const Utils::FilePaths &files, const CppEditor::ProjectPart &part);
+    QStringList additionalArguments(const CppEditor::ProjectPart &part) const;
 
     CppcheckDiagnosticManager &m_manager;
     CppcheckOptions m_options;