Enable VideoToolbox AV1 decode

This decoder differs from others provided by VideoToolbox in that it lacks any software fallback. To achieve consistent behavior with other VideoToolbox decoders, this PR implemented additional checking on the server to simulate the software fallback provided by VideoToolbox.

The current fallback checking mechanism is a temporary solution. In the long term, it should be replaced with a more capable hardware capability checking system.

MediaBrowser.Controller/MediaEncoding/IMediaEncoder.cs

@@ -75,6 +75,12 @@ namespace MediaBrowser.Controller.MediaEncoding
         /// <value><c>true</c> if the Vaapi device supports vulkan drm interop, <c>false</c> otherwise.</value>
         bool IsVaapiDeviceSupportVulkanDrmInterop { get; }
 
+        /// <summary>
+        /// Gets a value indicating whether av1 decoding is available via VideoToolbox.
+        /// </summary>
+        /// <value><c>true</c> if the av1 is available via VideoToolbox, <c>false</c> otherwise.</value>
+        bool IsVideoToolboxAv1DecodeAvailable { get; }
+
         /// <summary>
         /// Whether given encoder codec is supported.
         /// </summary>