Add AudioVolumeField -- cleanup (#1107)

* WIP Adding AudioVolumeField

* Fix build break

* Add Bernd to about

---------

Co-authored-by: kallanreed <kallanreed@outlook.com>

firmware/application/ui/ui_receiver.hpp

@@ -337,6 +337,11 @@ class VGAGainField : public NumberField {
     void on_focus() override;
 };
 
+class AudioVolumeField : public NumberField {
+   public:
+    AudioVolumeField(Point parent_pos);
+};
+
 } /* namespace ui */
 
 #endif /*__UI_RECEIVER_H__*/