connect method
Sets the Dart Tooling Daemon connection to point to uri.
Before connecting to uri, if a current connection exists, then
disconnect is called to close it.
Implementation
Future<void> connect(
  Uri uri, {
  void Function(Object, StackTrace?)? onError,
}) async {
  await disconnect();
  try {
    _connection.value = await DartToolingDaemon.connect(uri);
    _uri = uri;
    _log.info('Successfully connected to DTD at: $uri');
  } catch (e, st) {
    onError?.call(e, st);
  }
}