Add multiple audio backend framework

RedBookPlayer.Models/Hardware/IAudioBackend.cs

@@ -0,0 +1,30 @@
+namespace RedBookPlayer.Models.Hardware
+{
+    public interface IAudioBackend
+    {
+        /// <summary>
+        /// Pauses the audio playback
+        /// </summary>
+        void Pause();
+
+        /// <summary>
+        /// Starts the playback.
+        /// </summary>
+        void Play();
+
+        /// <summary>
+        /// Stops the audio playback
+        /// </summary>
+        void Stop();
+
+        /// <summary>
+        /// Get the current playback state
+        /// </summary>
+        PlayerState GetPlayerState();
+
+        /// <summary>
+        /// Set the new volume value
+        /// </summary>
+        void SetVolume(float volume);
+    }
+}