Use sb3 and gymnasium as much as possible rather then hide imports in rlberry's API

[KohlerHECTOR]

Rather than using rlberry.envs.gym_make let us use gymnasium.make Rather than using rlberry.agents.torch let us use rlberry.agents.stable_baselines Same for atari_make and spaces.... basically if an rlberry class is just import a gymnasium or sb3 method, let us remvove it from rlberry api