Refactor app orchestrator into Application with dependency injection

js/applicationContext.js

@@ -0,0 +1,24 @@
+// js/applicationContext.js
+
+let applicationInstance = null;
+let readyPromise = Promise.resolve();
+
+export function setApplication(app) {
+  applicationInstance = app || null;
+}
+
+export function getApplication() {
+  return applicationInstance;
+}
+
+export function setApplicationReady(promise) {
+  if (promise && typeof promise.then === "function") {
+    readyPromise = promise;
+  } else {
+    readyPromise = Promise.resolve(promise);
+  }
+}
+
+export function getApplicationReady() {
+  return readyPromise;
+}