feat(CommandInteraction): ephemeral followup messages (#5618)

Co-authored-by: Antonio Román <kyradiscord@gmail.com>

src/structures/CommandInteraction.js

@@ -187,6 +187,24 @@ class CommandInteraction extends Interaction {
    * @property {Role|Object} [role] The resolved role
    */
 
+  /**
+   * Send a follow-up message to this interaction.
+   * @param {string|APIMessage|MessageAdditions} content The content for the reply
+   * @param {InteractionReplyOptions} [options] Additional options for the reply
+   * @returns {Promise<Message|Object>}
+   */
+  async followUp(content, options) {
+    const apiMessage = content instanceof APIMessage ? content : APIMessage.create(this, content, options);
+    const { data, files } = await apiMessage.resolveData().resolveFiles();
+
+    const raw = await this.client.api.webhooks(this.applicationID, this.token).post({
+      data,
+      files,
+    });
+
+    return this.channel?.messages.add(raw) ?? raw;
+  }
+
   /**
    * Transforms an option received from the API.
    * @param {Object} option The received option