Move completion settings page to TextEditor plugin.

Change-Id: I12b7828d23d599e5903237d0cc2a3c0440e1b07d
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

src/plugins/texteditor/codeassist/codeassistant.h

@@ -47,7 +47,6 @@ public:
     ~CodeAssistant();
 
     void configure(TextEditorWidget *editorWidget);
-    void updateFromCompletionSettings(const TextEditor::CompletionSettings &settings);
 
     void process();
     void notifyChange();