[Feature] Make RL4CO Lightning Module work adaptively with or without Hydra

[Federico Berto]

It would be good to have the module to adaptively take either:

1. Configuration and instantiate with hydra.utils.instantiate
2. Env and model previously initialized

This would be very useful for people who do not know how to use Hydra, since it might be easier to just manually pass the model instead.
Config could still be passed as a DictConfig