Add override keyword in codebase (#120755)

For #120675

This uses a script to add the override keyword to places that need it in the codebase

Note that we can't enable the --noImplicitOverride setting yet since there are still around 200 errors that require further attention

src/vs/workbench/api/common/extHostNotebookDocument.ts

@@ -160,7 +160,7 @@ export class ExtHostNotebookDocument extends Disposable {
 		super();
 	}
 
-	dispose() {
+	override dispose() {
 		this._disposed = true;
 		super.dispose();
 		dispose(this._cellDisposableMapping.values());