Split common and GUI code into separate projects

RedBookPlayer.GUI/Program.cs

@@ -0,0 +1,29 @@
+using System;
+#if WindowsDebug
+using System.Runtime.InteropServices;
+#endif
+using Avalonia;
+using Avalonia.Logging.Serilog;
+
+namespace RedBookPlayer.GUI
+{
+    internal class Program
+    {
+        [STAThread]
+        public static void Main(string[] args)
+        {
+#if WindowsDebug
+            AllocConsole();
+#endif
+            BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
+        }
+
+#if WindowsDebug
+        [DllImport("kernel32.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        static extern bool AllocConsole();
+#endif
+
+        public static AppBuilder BuildAvaloniaApp() => AppBuilder.Configure<App>().UsePlatformDetect().LogToDebug();
+    }
+}