feat: ported action definition from setup-terraform

Signed-off-by: Dmitry Kisler <admin@dkisler.com>

wrapper/lib/output-listener.js

@@ -0,0 +1,41 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+/**
+ * Acts as a listener for @actions/exec, by capturing STDOUT and STDERR
+ * streams, and exposing them via a contents attribute.
+ *
+ * @example
+ * // Instantiate a new listener
+ * const listener = new OutputListener();
+ * // Register listener against STDOUT stream
+ * await exec.exec('ls', ['-ltr'], {
+ *  listeners: {
+ *    stdout: listener.listener
+ *  }
+ * });
+ * // Log out STDOUT contents
+ * console.log(listener.contents);
+ */
+class OutputListener {
+  constructor () {
+    this._buff = [];
+  }
+
+  get listener () {
+    const listen = function listen (data) {
+      this._buff.push(data);
+    };
+    return listen.bind(this);
+  }
+
+  get contents () {
+    return this._buff
+      .map(chunk => chunk.toString())
+      .join('');
+  }
+}
+
+module.exports = OutputListener;