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/api/node/sqlExtHost.api.impl.ts

@@ -496,7 +496,8 @@ export function createApiFactory(
 				registerNotebookProvider(provider: azdata.nb.NotebookProvider): vscode.Disposable {
 					return extHostNotebook.registerNotebookProvider(provider);
 				},
-				CellRange: sqlExtHostTypes.CellRange
+				CellRange: sqlExtHostTypes.CellRange,
+				NotebookChangeKind: sqlExtHostTypes.NotebookChangeKind
 			};
 
 			return {