move street view cover button to the map as circleControl

public/static/css/map_editor.css

@@ -55,6 +55,12 @@
     visibility: hidden;
 }
 
+#overlayControl {
+    bottom: 20px;
+    right: 10px;
+    z-index: 3;
+}
+
 #deleteButton {
     display: none;
 }