Refactor Vue components using Composition API #230

- Migrate `StatefulVue`:
  - Introduce `UseCollectionState` that replaces its behavior and acts
    as a shared state store.
  - Add more encapsulated, granular functions based on read or write
    access to state in CollectionState.
- Some linting rules get activates due to new code-base compability to
  modern parses, fix linting errors.
  - Rename Dialog to ModalDialog as after refactoring,
    eslintvue/no-reserved-component-names does not allow name Dialog.
  - To comply with `vue/multi-word-component-names`, rename:
    - `Code`          -> `CodeInstruction`
    - `Handle`        -> `SliderHandle`
    - `Documentable`  -> `DocumentableNode`
    - `Node`          -> `NodeContent`
    - `INode`         -> `INodeContent`
    - `Responsive`    -> `SizeObserver`
- Remove `vue-property-decorator` and `vue-class-component`
  dependencies.
- Refactor `watch` with computed properties when possible for cleaner
  code.
  - Introduce `UseApplication` to reduce repeated code in new components
    that use `computed` more heavily than before.
- Change TypeScript target to `es2017` to allow top level async calls
  for getting application context/state/instance to simplify the code by
  removing async calls. However, mocha (unit and integration) tests do
  not run with top level awaits, so a workaround is used.

tests/unit/shared/Stubs/EventSourceStub.ts

@@ -0,0 +1,22 @@
+import { EventHandler, IEventSource, IEventSubscription } from '@/infrastructure/Events/IEventSource';
+import { EventSubscriptionStub } from './EventSubscriptionStub';
+
+export class EventSourceStub<T> implements IEventSource<T> {
+  private readonly handlers = new Array<EventHandler<T>>();
+
+  public on(handler: EventHandler<T>): IEventSubscription {
+    this.handlers.push(handler);
+    return new EventSubscriptionStub(() => {
+      const index = this.handlers.indexOf(handler);
+      if (index !== -1) {
+        this.handlers.splice(index, 1);
+      }
+    });
+  }
+
+  public notify(data: T) {
+    for (const handler of this.handlers) {
+      handler(data);
+    }
+  }
+}