Add support for reading and storing Recording MBIDs from file metadata (#12173)

* Add recording metadata provider

* Add recording MBID

* Save recording MBID during probing

* Set recording ID in probe result normalizer

* Add recording external media type

* Reimplement after changes in upstream

* Rename variable

* Rename variable

* Revert "Set recording ID in probe result normalizer"

This reverts commit 9dd18c8aba.

* Fix setting provider ID

* Simplify code

* Fix comment

* Add missing using

MediaBrowser.Model/Providers/ExternalIdMediaType.cs

@@ -71,6 +71,11 @@ namespace MediaBrowser.Model.Providers
         /// <summary>
         /// A book.
         /// </summary>
-        Book = 13
+        Book = 13,
+
+        /// <summary>
+        /// A music recording.
+        /// </summary>
+        Recording = 14
     }
 }