Replaced volume controls floater with panel on Latency skin

indra/newview/app_settings/settings.xml

@@ -20775,5 +20775,16 @@ Change of this parameter will affect the layout of buttons in notification toast
       <key>Value</key>
       <integer>0</integer>
     </map>
+    <key>FSVolumeControlsPanelOpen</key>
+    <map>
+      <key>Comment</key>
+      <string>Internal control for visibility of volume control panel.</string>
+      <key>Persist</key>
+      <integer>0</integer>
+      <key>Type</key>
+      <string>Boolean</string>
+      <key>Value</key>
+      <integer>0</integer>
+    </map>
 </map>
 </llsd>