[Feature Request] Dict Obs Spaces Support

[alexpalms]

🚀 Feature

As far as I understood by some preliminar tests, SBX currently does not support Dict observation spaces, do you have this feature in your roadmap? If yes when is it expected to be added?

Motivation

It would allow to extend the list of supported use cases featuring more complex/structured observation spaces

### Checklist

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

[araffin]

Hello,
SBX has a limited support for it (when all the items are boxes).

do you have this feature in your roadmap? If yes when is it expected to be added?

Not yet, I would prefer to have CNN support first.

Are you willing to contribute full support for dict obs?

[alexpalms]

Thanks for the feedback @araffin, I'd love to contribute to the project, but for now is hard to find the bandwidth.

I also agree with the CNN priority, the dict limitation can easily be worked around by using a custom flattening wrapper.

I will reach out if I manage to allocate some time, thanks!