fix(record-mode): handle missing teleop device in gym_hil environments

[hcooch2ch3]

What this does

Title	Label
Fixes #2000, Fixes #2155	🐛 Bug

In gym_hil (Hardware-In-the-Loop) simulation environments where no teleop device is available, the record mode was failing with a AttributeError when trying to access teleop_device.action_features.

This fix checks if a teleop device is available and:

• Uses teleop_device.action_features when available (normal case)
• Falls back to deriving action features from the environment's action space when teleop device is None (gym_hil case)

This allows users to record trajectories in simulation environments without a physical teleop device.

How it was tested

• Verified the code handles a case without teleop device
• The action features are correctly derived from env.action_space with dtype "float32" and appropriate shape
• Record mode can now proceed without throwing an error in gym_hil environments

How to checkout & try?

Record trajectories in a gym_hil environment without teleop device

1. Make gym_hil_env.json file like this:

{
  "env": {
    "name": "gym_hil",
    "task": "PandaPickCubeKeyboard-v0",
    "fps": 10,
    "processor": {
      "control_mode": "keyboard",
      "gripper": {
        "use_gripper": true,
        "gripper_penalty": -0.02
      },
      "reset": {
        "fixed_reset_joint_positions": [0.0, 0.195, 0.0, -2.43, 0.0, 2.62, 0.785],
        "reset_time_s": 2.0,
        "control_time_s": 15.0,
        "terminate_on_success": false
      }
    }
  },
  "dataset": {
    "repo_id": "aractingi/franka_sim_pick_lift_6",
    "root": "/Users/yimsungmin/lerobot/my_hil_dataset/PandaPickCubeKeyboard-v0/",
    "task": "pick_cube",
    "num_episodes_to_record": 1,
    "replay_episode": 0,
    "push_to_hub": false
  },
  "mode": "record",
  "device": "mps"
}

2. Launch the simulator(gym_hil) and start recording using:

mjpython -m lerobot.rl.gym_manipulator --config_path ./gym_hil_env.json

3. Check Recorded Data
   The recorded dataset of simulation will be saved in the specified directory.