feat(Interactions): add InteractionWebhook for better internals (#5712)

src/structures/InteractionWebhook.js

@@ -0,0 +1,44 @@
+'use strict';
+
+const Webhook = require('./Webhook');
+
+/**
+ * Represents a webhook for an Interaction
+ * @implements {Webhook}
+ */
+class InteractionWebhook {
+  /**
+   * @param {Client} client The instantiating client
+   * @param {Snowflake} id ID of the application
+   * @param {string} token Token of the interaction
+   */
+  constructor(client, id, token) {
+    /**
+     * The client that instantiated the interaction webhook
+     * @name InteractionWebhook#client
+     * @type {Client}
+     * @readonly
+     */
+    Object.defineProperty(this, 'client', { value: client });
+    this.id = id;
+    Object.defineProperty(this, 'token', { value: token, writable: true, configurable: true });
+  }
+
+  // These are here only for documentation purposes - they are implemented by Webhook
+  /* eslint-disable no-empty-function, valid-jsdoc */
+  /**
+   * Sends a message with this webhook.
+   * @param {string|APIMessage|MessageAdditions} content The content for the reply
+   * @param {InteractionReplyOptions} [options] Additional options for the reply
+   * @returns {Promise<Message|Object>}
+   */
+  send() {}
+  fetchMessage() {}
+  editMessage() {}
+  deleteMessage() {}
+  get url() {}
+}
+
+Webhook.applyToClass(InteractionWebhook, ['sendSlackMessage', 'edit', 'delete', 'createdTimestamp', 'createdAt']);
+
+module.exports = InteractionWebhook;