LLM Version - Terra Baselines

[gioelemo]

This PR introduces the support to LLM (pure llm and hybrid approach). For more details consults the corresponding README.md file.

The only changed file is the model.py: I have added a function to support loading the RL policy for a single environment instead of a batch environment.
There are

def get_model_ready(rng, config, env: TerraEnvBatch, speed=False): for Batch environment
def get_model_ready(rng, config, env: TerraEnv, speed=False): for single environment

Both function should work depending on the type of parameters.

All the other files are new and separate from the other part of this repository.

[gioelemo]

@Idate96 I'm unable to request a review directly since I don't have the necessary permissions for this repository (unlike Terra, who does have access). Could you grant me the appropriate rights? This would allow me to request reviews directly through Copilot. Thanks!