Adopt webworker search for local files in browser (#133366)

* Revert "Revert commits intended for PR"

This reverts commit f01d9ab212.

* Publicise getHandle rather than getDirectoryHandle

* Restore languagedetection export

* Try more targetted fix for overquerying

* Handle webworker search errors

build/gulpfile.vscode.js

@@ -40,6 +40,7 @@ const vscodeEntryPoints = _.flatten([
 	buildfile.workerExtensionHost,
 	buildfile.workerNotebook,
 	buildfile.workerLanguageDetection,
+	buildfile.workerLocalFileSearch,
 	buildfile.workbenchDesktop,
 	buildfile.code
 ]);