[Feature] Add missing VoiceChannel properties (#2573)

* add missing properties

* forgot about `MockedVoiceChannel`

src/Discord.Net.Core/Entities/Channels/IVoiceChannel.cs

@@ -26,6 +26,11 @@ namespace Discord
         /// </returns>
         int? UserLimit { get; }
 
+        /// <summary>
+        ///     Gets the video quality mode for this channel.
+        /// </summary>
+        VideoQualityMode VideoQualityMode { get; }
+
         /// <summary>
         ///     Bulk-deletes multiple messages.
         /// </summary>

src/Discord.Net.Core/Entities/Channels/VideoQualityMode.cs

@@ -0,0 +1,17 @@
+namespace Discord;
+
+/// <summary>
+///     Represents a video quality mode for voice channels.
+/// </summary>
+public enum VideoQualityMode
+{
+    /// <summary>
+    ///     Discord chooses the quality for optimal performance.
+    /// </summary>
+    Auto = 1,
+
+    /// <summary>
+    /// 	720p.
+    /// </summary>
+    Full = 2
+}

src/Discord.Net.Core/Entities/Channels/VoiceChannelProperties.cs

@@ -17,5 +17,10 @@ namespace Discord
         ///     Gets or sets the channel voice region id, automatic when set to <see langword="null"/>.
         /// </summary>
         public Optional<string> RTCRegion { get; set; }
+
+        /// <summary>
+        ///     Get or sets the video quality mode for this channel.
+        /// </summary>
+        public Optional<VideoQualityMode> VideoQualityMode { get; set; }
     }
 }