Reorganize config to use dataclasses + do automatic parsing using Hydra

[cgokmen]

Right now it is very difficult to follow configs: what are the defaults? What are the possible values? Lots of kwargs passing around happening etc. - we want to change this by creating explicit config classes and storing and passing those, like what Isaac Lab does. We also want to use a clever config loading mechanism like Hydra to void the difficulty of serialization.