feat(toolbar-button-clicked) Enhance toolbar buttons with notify click

- add possibility to allow execution of the button's routine besides triggering
`toolbarButtonClicked` API event
- keep backwards compatibility
- get rid of `ToolbarButton`

react/features/feedback/components/FeedbackButton.web.js

@@ -40,13 +40,7 @@ class FeedbackButton extends AbstractButton<Props, *> {
      * @returns {void}
      */
     _handleClick() {
-        const { _conference, dispatch, handleClick } = this.props;
-
-        if (handleClick) {
-            handleClick();
-
-            return;
-        }
+        const { _conference, dispatch } = this.props;
 
         sendAnalytics(createToolbarEvent('feedback'));
         dispatch(openFeedbackDialog(_conference));