Supports sb3 wrapper to pre-process env's image obs-space to trigger sb3 natively supported cnn creation pipeline (#2812)

# Description

This PR modifies the SB3 Wrapper so that it utilizes the 
SB3 natively supported encoder creation on properly defined composite
observation space,

SB3's automatic CNN encoding will apply when
1. if observation space of that term is of shape, GrayScale, RGB, or
RGBD
2. if agent_cfg has normalized flag, expects data to have channel as the
first dimension, and data pre_normalized
3. if agent doesn't has normalized flag, expects data to have space
min=0, max=255, dtype=uint8

This PR makes sure the sb3 wrapper adjust environment image term to meet
either condition 2 or condition 3 by looking at space's min and max, so
sb3 creation pipeline will be applied automatically.


## Type of change

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- New feature (non-breaking change which adds functionality)

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## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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Co-authored-by: Kelly Guo <kellyg@nvidia.com>