Add display of sample rate

src/widget-sample-rate.h

@@ -0,0 +1,12 @@
+// SPDX-FileCopyrightText: 2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#include "alsa.h"
+
+GtkWidget *make_sample_rate_widget(
+  struct alsa_card *alsa_card
+);