[Feature Request] Create another type of BaseEnv that does not require action/observation spaces.

[Bas van der Heijden]

🚀 Feature

As of now, all inputs and outputs of an environment require a fully defined Space. However, if we would like to use the environment in settings other than with RL, this requirement might be too strict.

Checklist

• I have checked that there is no similar issue in the repo (required)