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/extHostDocumentData.ts

@@ -42,7 +42,7 @@ export class ExtHostDocumentData extends MirrorTextModel {
 		super(uri, lines, eol, versionId);
 	}
 
-	dispose(): void {
+	override dispose(): void {
 		// we don't really dispose documents but let
 		// extensions still read from them. some
 		// operations, live saving, will now error tho