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/base/toolbox/components/AbstractAudioMuteButton.js

@@ -23,14 +23,6 @@ export default class AbstractAudioMuteButton<P: Props, S: *>
      * @returns {void}
      */
     _handleClick() {
-        const { handleClick } = this.props;
-
-        if (handleClick) {
-            handleClick();
-
-            return;
-        }
-
         this._setAudioMuted(!this._isAudioMuted());
     }