fix(remote-menu): show volume slider whenever available

css/_popup_menu.scss

 **/
 
 .popupmenu {
+    min-width: 75px;
     text-align: left;
     padding: 0;
     white-space: nowrap;

react/features/remote-video-menu/components/RemoteVideoMenuTriggerButton.js

             );
         }
 
-        if (onVolumeChange && isModerator) {
+        if (onVolumeChange) {
             buttons.push(
                 <VolumeSlider
                     initialValue = { initialVolumeValue }