add mp4 to MediaDataPartType enum (dotnet#1866)

Author: mikeebowen

src/DocumentFormat.OpenXml.Framework/Packaging/MediaDataPartType.cs

@@ -125,6 +125,11 @@ public enum MediaDataPartType
         /// </summary>
         VC1,
 
+        /// <summary>
+        /// MP4 Stream (.mp4)
+        /// </summary>
+        Mp4,
+
         #endregion
     }
 }

src/DocumentFormat.OpenXml.Framework/Packaging/MediaDataPartTypeInfo.cs

@@ -39,6 +39,7 @@ internal static string GetContentType(this MediaDataPartType mediaDataPartType)
                 MediaDataPartType.Quicktime => "video/quicktime",
                 MediaDataPartType.OggVideo => "video/ogg",
                 MediaDataPartType.VC1 => "video/vc1",
+                MediaDataPartType.Mp4 => "video/mp4",
                 _ => throw new ArgumentOutOfRangeException(nameof(mediaDataPartType)),
             };
 
@@ -74,6 +75,7 @@ internal static string GetTargetExtension(this MediaDataPartType mediaDataPartTy
                 MediaDataPartType.Quicktime => ".mov",
                 MediaDataPartType.OggVideo => ".ogg",
                 MediaDataPartType.VC1 => ".wmv",
+                MediaDataPartType.Mp4 => ".mp4",
                 _ => ".media",
             };
     }

src/DocumentFormat.OpenXml.Framework/PublicAPI/PublicAPI.Shipped.txt

@@ -498,6 +498,7 @@ DocumentFormat.OpenXml.Packaging.MediaDataPartType.Asx = 8 -> DocumentFormat.Ope
 DocumentFormat.OpenXml.Packaging.MediaDataPartType.Avi = 9 -> DocumentFormat.OpenXml.Packaging.MediaDataPartType
 DocumentFormat.OpenXml.Packaging.MediaDataPartType.Midi = 1 -> DocumentFormat.OpenXml.Packaging.MediaDataPartType
 DocumentFormat.OpenXml.Packaging.MediaDataPartType.Mp3 = 2 -> DocumentFormat.OpenXml.Packaging.MediaDataPartType
+DocumentFormat.OpenXml.Packaging.MediaDataPartType.Mp4 = 18 -> DocumentFormat.OpenXml.Packaging.MediaDataPartType
 DocumentFormat.OpenXml.Packaging.MediaDataPartType.MpegAudio = 6 -> DocumentFormat.OpenXml.Packaging.MediaDataPartType
 DocumentFormat.OpenXml.Packaging.MediaDataPartType.MpegUrl = 3 -> DocumentFormat.OpenXml.Packaging.MediaDataPartType
 DocumentFormat.OpenXml.Packaging.MediaDataPartType.MpegVideo = 11 -> DocumentFormat.OpenXml.Packaging.MediaDataPartType