CodeStyle: Remove edit pop-up

Removed the Edit pop-up on the CodeStyle page.
Now editing is available immediately after opening
CodeStyle tab.
I left a preview on the project CodeStyle page and
added a link to global settings.

ToDo:
In project CodeStyle page replace preview with CodeStyleEditor.
I'm not 100% sure that it is needed. If you have some thoughts
please write a comment.

Change-Id: I31032a97b9668b4f6b06fc6c5c704700fb44ee4f
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/texteditor/codestyleeditor.h

@@ -50,6 +50,7 @@ public:
                     QWidget *parent = nullptr);
 
     void apply() override;
+    void finish() override;
 private:
     void updatePreview();
 
@@ -58,6 +59,7 @@ private:
     ICodeStylePreferences *m_codeStyle;
     SnippetEditorWidget *m_preview;
     CodeStyleEditorWidget *m_additionalGlobalSettingsWidget;
+    CodeStyleEditorWidget *m_widget;
 };
 
 } // namespace TextEditor