Brax

- Fix bug in rendering cylinders and planes.
- Fix issue with link offsets in `io.mjcf.load_model`.

Brax Release Notes

* Fixes 460, 461, and an issue related to 353.
* Removes barkour v0 joystick policy in favor of the [MJX tutorial](https://colab.research.google.com/github/google-deepmind/mujoco/blob/main/mjx/tutorial.ipynb) training barkour vb.
* Fixes 466.

This minor release makes several changes to the brax API, such that [MJX](https://mujoco.readthedocs.io/en/stable/mjx.html) data structures are the core data structures used in brax. This allows for more seamless model loading from `MuJoCo` XMLs, and allows for running `MJX` physics more seamlessly in brax.

* Rebase brax `System` and `State` onto `mjx.Model` and `mjx.Data`.
* Separate validation logic from the model loading logic in `brax.io.mjcf`. This allows users to load an [MJX](https://mujoco.readthedocs.io/en/stable/mjx.html) model in brax, without hitting validation errors for other physics backends like `positional` and `spring`.
* Remove `System.geoms`, since `brax.System` inherits from `mjx.Model` and all geom information is available in `mjx.Model`. We also update the brax viewer to work with this new schema.
* Delete the brax contact library and use the contact library from `MJX`.
* Use the MuJoCo renderer instead of pytinyrenderer for `brax.io.image`.

* Fixes gradients for generalized by changing a jp.linalg.norm to safe_norm.
* Adds the [MJX](https://mujoco.readthedocs.io/en/stable/mjx.html) pipeline to Brax as well as an MjxEnv for RL training.

This patch release:

* Fixes compatibility issues with MuJoCo 3.0.0
* Fixes bugs with gym and dm envs.

This patch release:
* Adds domain randomization module
* Adds swimmer env
* Adds barkour env to experimental