feat: get pinned messages (#3004)

* feat: add getPinnedMessage method

* docs: add docs for the method

* chore: fix eslint

* refactor: change logic of getting pinned messages

* refactor: combine all PinnedMsgUtils

* chore: remove comments and mark as ready for review

* style: fix typo

Co-authored-by: crazynds <36674096+crazynds@users.noreply.github.com>

---------

Co-authored-by: crazynds <36674096+crazynds@users.noreply.github.com>

src/structures/Chat.js

@@ -279,6 +279,14 @@ class Chat extends Base {
         return this.client.addOrRemoveLabels(labelIds, [this.id._serialized]);
     }
 
+    /**
+     * Gets instances of all pinned messages in a chat
+     * @returns {Promise<[Message]|[]>}
+     */
+    async getPinnedMessages() {
+        return this.client.getPinnedMessages(this.id._serialized);
+    }
+    
     /**
      * Sync chat history conversation
      * @return {Promise<boolean>} True if operation completed successfully, false otherwise.