Add example with the Candlewick visualizer

[stephane-caron]

This PR adds a visualization example using Candlewick, a renderer (based on SDL_gpu) for robot descriptions loaded in Pinocchio:

python show_in_candlewick.py spot_mj

[coveralls]

Pull Request Test Coverage Report for Build 14269410358

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 97.89%

---

Totals
Change from base Build 14197758126:	0.0%
Covered Lines:	1067
Relevant Lines:	1090

---

💛 - Coveralls