disconnect method
Closes and unsets the Dart Tooling Daemon connection, if one is set.
Implementation
Future<void> disconnect() async {
  if (_connection.value != null) {
    await _connection.value!.close();
  }
  _connection.value = null;
  _uri = null;
  _workspaceRoots = null;
  _projectRoots = null;
}