[FEATURE] WIP: Differentiable forward dynamics for rigid body simulation

[SonSang]

Description

This PR has following changes:

1. Unify hibernation / non-hibernation code in rigid_solver_decomp.py
2. Adding frame dimension to the rigid body states, so that it stores intermediate states during simulation for differentiability
3. Differentiable (rigid body) forward dynamics

Related Issue

Resolves Genesis-Embodied-AI/Genesis#

Motivation and Context

This is the part of the process to make the rigid body simulation to be differentiable.

How Has This Been / Can This Be Tested?

Screenshots (if appropriate):

Checklist:

• I read the CONTRIBUTING document.
• I followed the Submitting Code Changes section of CONTRIBUTING document.
• I tagged the title correctly (including BUG FIX/FEATURE/MISC/BREAKING)
• I updated the documentation accordingly or no change is needed.
• I tested my changes and added instructions on how to test it for reviewers.

• I have added tests to cover my changes.
• All new and existing tests passed.