CppTools: Move CppHoverHandler to CppTools

This is in preparation for clang code model to provide its own hover
handler.

Change-Id: Ifbdd96f427989bd5d1fbc4badb9c38108485c2f2
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/plugins/clangcodemodel/clangmodelmanagersupport.h

@@ -61,6 +61,7 @@ public:
     ~ModelManagerSupportClang();
 
     CppTools::CppCompletionAssistProvider *completionAssistProvider() override;
+    TextEditor::BaseHoverHandler *createHoverHandler() override;
     CppTools::BaseEditorDocumentProcessor *createEditorDocumentProcessor(
                 TextEditor::TextDocument *baseTextDocument) override;
     CppTools::FollowSymbolInterface &followSymbolInterface() override;