Add saved and executed events to notebook changed (#5848)

- Updated the notebook API to add a change kind, and support saved, executed and other simplified status
- Plumbed this through to the main thread classes
- Support sending the events from cell / input to the notebook model so they loop over the extension host as a content changed event
- Add executed event from the cell

src/sql/workbench/parts/notebook/notebook.component.ts

@@ -345,7 +345,7 @@ export class NotebookComponent extends AngularDisposable implements OnInit, OnDe
 
 	private get modelFactory(): IModelFactory {
 		if (!this._notebookParams.modelFactory) {
-			this._notebookParams.modelFactory = new ModelFactory();
+			this._notebookParams.modelFactory = new ModelFactory(this.instantiationService);
 		}
 		return this._notebookParams.modelFactory;
 	}