Start the dashboard.

def start_dashboard(self):
        """Start the dashboard."""
        stdout_file, stderr_file = self.new_log_files("dashboard", True)
        self._webui_url, process_info = ray.services.start_dashboard(
            self.redis_address,
            self._temp_dir,
            stdout_file=stdout_file,
            stderr_file=stderr_file,
            redis_password=self._ray_params.redis_password)
        assert ray_constants.PROCESS_TYPE_DASHBOARD not in self.all_processes
        if process_info is not None:
            self.all_processes[ray_constants.PROCESS_TYPE_DASHBOARD] = [
                process_info
            ]
            redis_client = self.create_redis_client()
            redis_client.hmset("webui", {"url": self._webui_url})