feat(GuildPreview): add createdAt & createdTimestamp (#6130)

Co-authored-by: SpaceEEC <spaceeec@yahoo.com>

src/structures/GuildPreview.js

@@ -3,6 +3,7 @@
 const Base = require('./Base');
 const GuildPreviewEmoji = require('./GuildPreviewEmoji');
 const Collection = require('../util/Collection');
+const SnowflakeUtil = require('../util/SnowflakeUtil');
 
 /**
  * Represents the data about the guild any bot can preview, connected to the specified guild.
@@ -90,6 +91,23 @@ class GuildPreview extends Base {
       this.emojis.set(emoji.id, new GuildPreviewEmoji(this.client, emoji, this));
     }
   }
+  /**
+   * The timestamp this guild was created at
+   * @type {number}
+   * @readonly
+   */
+  get createdTimestamp() {
+    return SnowflakeUtil.deconstruct(this.id).timestamp;
+  }
+
+  /**
+   * The time this guild was created at
+   * @type {Date}
+   * @readonly
+   */
+  get createdAt() {
+    return new Date(this.createdTimestamp);
+  }
 
   /**
    * The URL to this guild's splash.