Add common, refactor eval with eval_policy

lerobot/common/utils.py

@@ -0,0 +1,12 @@
+import random
+
+import numpy as np
+import torch
+
+
+def set_seed(seed):
+    """Set seed for reproducibility."""
+    random.seed(seed)
+    np.random.seed(seed)
+    torch.manual_seed(seed)
+    torch.cuda.manual_seed_all(seed)