Added FirefoxStrategy to interact with the Firefox extension for Postwoman

functions/strategies/FirefoxStrategy.js

@@ -0,0 +1,15 @@
+const firefoxStrategy = (req, _store) => new Promise((resolve, reject) => {
+
+  const eventListener = (event) => {
+    window.removeEventListener("firefoxExtSendRequestComplete", eventListener);
+
+    if (event.detail.error) reject(JSON.parse(event.detail.error));
+    else resolve(JSON.parse(event.detail.response));
+  };
+
+  window.addEventListener("firefoxExtSendRequestComplete", eventListener);
+
+  window.firefoxExtSendRequest(req);
+});
+
+export default firefoxStrategy;