[Feature] Add missing property & new stuff (#2521)

* add active developer badge support

* add `OwnerId` to threads

* add default forum layout support

* oops, forgot to update modifyasync

* add missing application flags

* Add `50155` error code

src/Discord.Net.WebSocket/Entities/Channels/SocketForumChannel.cs

@@ -45,6 +45,9 @@ namespace Discord.WebSocket
         /// <inheritdoc/>
         public ForumSortOrder? DefaultSortOrder { get; private set; }
 
+        /// <inheritdoc />
+        public ForumLayout DefaultLayout { get; private set; }
+
         /// <summary>
         ///     Gets the parent (category) of this channel in the guild's channel list.
         /// </summary>
@@ -93,6 +96,8 @@ namespace Discord.WebSocket
             }
 
             CategoryId = model.CategoryId.GetValueOrDefault();
+
+            DefaultLayout = model.DefaultForumLayout.GetValueOrDefault();
         }
 
         /// <inheritdoc />

src/Discord.Net.WebSocket/Entities/Channels/SocketThreadChannel.cs

@@ -95,6 +95,9 @@ namespace Discord.WebSocket
         /// <inheritdoc cref="IThreadChannel.CreatedAt"/>
         public override DateTimeOffset CreatedAt { get; }
 
+        /// <inheritdoc cref="IThreadChannel.OwnerId"/>
+        ulong IThreadChannel.OwnerId => _ownerId;
+
         /// <summary>
         ///     Gets a collection of cached users within this thread.
         /// </summary>