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/debugger/debuggertooltipmanager.cpp

@@ -42,7 +42,7 @@
 #include <coreplugin/editormanager/editormanager.h>
 #include <coreplugin/modemanager.h>
 
-#include <cpptools/cppprojectfile.h>
+#include <cppeditor/cppprojectfile.h>
 
 #include <projectexplorer/session.h>
 
@@ -1203,8 +1203,8 @@ void DebuggerToolTipManagerPrivate::slotTooltipOverrideRequested
     QString raw = cppExpressionAt(editorWidget, context.position, &context.line, &context.column,
                                   &context.function, &context.scopeFromLine, &context.scopeToLine);
     context.expression = fixCppExpression(raw);
-    context.isCppEditor = CppTools::ProjectFile::classify(document->filePath().toString())
-                            != CppTools::ProjectFile::Unsupported;
+    context.isCppEditor = CppEditor::ProjectFile::classify(document->filePath().toString())
+                            != CppEditor::ProjectFile::Unsupported;
 
     if (context.expression.isEmpty()) {
         ToolTip::show(point, DebuggerToolTipManager::tr("No valid expression"),