feat: support default_thread_rate_limit_per_user in channel creation

#9339 djs

src/structures/BaseGuildTextChannel.js

@@ -81,6 +81,16 @@ class BaseGuildTextChannel extends GuildChannel {
       this.defaultAutoArchiveDuration = data.default_auto_archive_duration;
     }
 
+    if ('default_thread_rate_limit_per_user' in data) {
+      /**
+       * The initial rate limit per user (slowmode) to set on newly created threads in a channel.
+       * @type {?number}
+       */
+      this.defaultThreadRateLimitPerUser = data.default_thread_rate_limit_per_user;
+    } else {
+      this.defaultThreadRateLimitPerUser ??= null;
+    }
+
     if ('messages' in data) {
       for (const message of data.messages) this.messages._add(message);
     }

src/structures/CategoryChannel.js

@@ -62,6 +62,8 @@ class CategoryChannel extends GuildChannel {
    * @property {?DefaultReactionEmoji} [defaultReactionEmoji] The emoji to set as the default reaction emoji
    * @property {number} [defaultThreadRateLimitPerUser] The rate limit per user (slowmode) to set on forum posts
    * @property {?SortOrderType} [defaultSortOrder] The default sort order mode to set on the new channel
+   * @property {number} [defaultThreadRateLimitPerUser] The initial rate limit per user (slowmode)
+   * to set on newly created threads in a channel.
    * @property {string} [reason] Reason for creating the new channel
    */