porting files in lib/ actions, reducers and utils/plugins to ts (#3887)

* add type definitions

* rename files in lib/actions

* rename files from lib/reducers to ts

* renamed plugins.js to ts

* Add hyper types

* Fix ts errors in lib/reducers

* Fix ts errors in lib/actions

* Fix ts errors in plugins.ts

lib/actions/notifications.ts

@@ -0,0 +1,17 @@
+import {NOTIFICATION_MESSAGE, NOTIFICATION_DISMISS} from '../constants/notifications';
+
+export function dismissNotification(id: string) {
+  return {
+    type: NOTIFICATION_DISMISS,
+    id
+  };
+}
+
+export function addNotificationMessage(text: string, url: string | null = null, dismissable = true) {
+  return {
+    type: NOTIFICATION_MESSAGE,
+    text,
+    url,
+    dismissable
+  };
+}