ClangFormat: Add disable option

- Added a possibility to disable ClangFormat plugin
- Removed unneeded properties from clangformatsettings

Change-Id: If71f46670e4fd3d2dac6d18c97df5a811504ed5e
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/clangformat/clangformatindenter.h

@@ -40,7 +40,6 @@ public:
 
 private:
     bool formatCodeInsteadOfIndent() const override;
-    bool formatWhileTyping() const override;
     int lastSaveRevision() const override;
 };