initial refresh backend selection API support

src/Refresh.cs

@@ -315,6 +315,14 @@ namespace RefreshCS
 			IntOpaqueWhite
 		}
 
+		public enum Backend
+		{
+			DontCare,
+			Vulkan,
+			PS5,
+			Invalid
+		}
+
 		/* Native Structures */
 
 		[StructLayout(LayoutKind.Sequential)]
@@ -585,6 +593,12 @@ namespace RefreshCS
 
 		/* Init/Quit */
 
+		[DllImport(nativeLibName, CallingConvention = CallingConvention.Cdecl)]
+		public static extern Backend Refresh_SelectBackend(
+			Backend preferredBackend,
+			out uint flags
+		);
+
 		[DllImport(nativeLibName, CallingConvention = CallingConvention.Cdecl)]
 		public static extern IntPtr Refresh_CreateDevice(
 			in PresentationParameters presentationParameters,