[Feature] Reproducible batched RNG support, fix state representations of various tasks

[StoneT2000]

• Adds batched RNG support, which is slower compared to using torch.rand or np.random and adding a batch dimension, but critically it ensures reproducibility regardless of the number of parallel environments. In the future perhaps we can replace it with some faster algorithm that can generate a batch of random numbers when given a batch of seeds (like jax rng).
• Fix state representation for tasks with object randomization that use actor/articulation merging