Begin abstracting global container into injector

src/lifecycle/AppClass.ts

@@ -1,5 +1,5 @@
 import {Application} from './Application'
-import {Container, DependencyKey} from '../di'
+import {Container, DependencyKey, Injectable} from '../di'
 
 /**
  * Base type for a class that supports binding methods by string.
@@ -25,12 +25,11 @@ export function isBindable(what: unknown): what is Bindable {
 /**
  * Base for classes that gives access to the global application and container.
  */
+@Injectable()
 export class AppClass {
     /** The global application instance. */
-    private readonly appClassApplication!: Application;
-
-    constructor() {
-        this.appClassApplication = Application.getApplication()
+    private get appClassApplication(): Application {
+        return Application.getApplication()
     }
 
     /** Get the global Application. */