[Feature Request] Add support for gymnasium.spaces.Text

### 🚀 Feature

Unless I'm mistaken, stable-baselines3 only supports Box, Discrete, MultiDiscrete, MultiBinary and Dict spaces from gymnasium.
It seems like a new _fundamental space_ has been introduced in Gymnasium ( [gymnasium.spaces.Text](https://gymnasium.farama.org/api/spaces/fundamental/#gymnasium.spaces.Text) ), which seems to be a more natural way to deal with text data.

### Motivation

This new support would ease the training of LLMs with RL.

### Pitch

_No response_

### Alternatives

One alternative is to use gymnasium.spaces.Box(low=0, high=vocab_size-1, dtype=np.int).
However this requires padding to support smaller texts.

### Additional context

_No response_

### Checklist

- [X] I have checked that there is no similar [issue](https://github.com/DLR-RM/stable-baselines3/issues) in the repo
- [X] If I'm requesting a new feature, I have proposed alternatives

Start with the Gymnasium Text space documentation linked in the issue and compare it with the currently supported Box, Discrete, MultiDiscrete, MultiBinary, and Dict spaces. Determine the project areas and tests affected by accepting Text spaces; done means Text observations or actions are supported without the padding workaround and existing space support remains intact.

Written by the indexing model from the issue text.