Speed-up video recording for Meshcat

New features and improvements:

• [Viewer] 'wait' methods no longer requires being parent of meshcat server
• [Viewer] Enable to set replay speed of recorded video
• [Viewer] Improve recording speed for meshcat from 2 fps to 10 fps by using latest Chrome version and Javascript WebM Writer
• [Viewer] Recorded video format is now '.webm' instead of '.mp4'

Patches and bug fixes:

• [Viewer] Make sure no orphan process is left behind at exit, with a clean backtrace, even for SIGTERM signal and Python exceptions
• [Viewer] Detach camera if it has been attached by play_trajectory
• [Viewer] Capture frame using Meshcat in ".webp" format instead of ".png" to improve efficiency
• [Viewer] Fix meshcat client redirection error when trailing backslash is missing in url