refactor(pipeline): Remove model card generation and streamline processor methods

- Eliminated the _generate_model_card method from RobotProcessor, which was responsible for generating README.md files from a template.
- Updated save_pretrained method to remove model card generation, focusing on serialization of processor definitions and parameters.
- Added default implementations for get_config, state_dict, load_state_dict, reset, and feature_contract methods in various processor classes to enhance consistency and usability.

tests/envs/test_envs.py

@@ -22,7 +22,7 @@ from gymnasium.utils.env_checker import check_env
 
 import lerobot
 from lerobot.envs.factory import make_env, make_env_config
-from lerobot.processor import RobotProcessor, TransitionKey, VanillaObservationProcessor
+from lerobot.envs.utils import preprocess_observation
 from tests.utils import require_env
 
 OBS_TYPES = ["state", "pixels", "pixels_agent_pos"]
@@ -48,12 +48,7 @@ def test_factory(env_name):
     cfg = make_env_config(env_name)
     env = make_env(cfg, n_envs=1)
     obs, _ = env.reset()
-
-    # Process observation using processor
-    obs_processor = RobotProcessor([VanillaObservationProcessor()])
-    transition = (obs, None, None, None, None, None, None)
-    processed_transition = obs_processor(transition)
-    obs = processed_transition[TransitionKey.OBSERVATION]
+    obs = preprocess_observation(obs)
 
     # test image keys are float32 in range [0,1]
     for key in obs: