Add muteControl to the list of controls of the control bar

The control bar is shown only when at least one control is selected
in the editor.

projects/common/element-components/control-bar/control-bar.component.html

@@ -3,6 +3,7 @@
     elementModel.showRestRuns ||
     elementModel.progressBar ||
     elementModel.showRestTime ||
+    elementModel.muteControl ||
     elementModel.volumeControl"
     class="control-bar"
     [class.hint-border]="showHint">