Add settings for fallback behavior

update action icon with padding

src/FocusVolumeControl/AudioSessions/IAudioSession.cs

@@ -0,0 +1,16 @@
+namespace FocusVolumeControl.AudioSessions;
+
+public interface IAudioSession
+{
+	public string DisplayName { get; }
+
+	public string GetIcon();
+
+	public void ToggleMute();
+
+	public bool IsMuted();
+
+	public void IncrementVolumeLevel(int step, int ticks);
+
+	public int GetVolumeLevel();
+}