Media Recording: Replace image segmentation library

[swissspidy]

Task Description

We currently use @mediapipe/selfie_segmentation for blurred background support when using the webcam.

This library is now being replaced by @mediapipe/tasks-vision, which is in early preview. We should start updating our usage accordingly.

Demo: https://codepen.io/mediapipe-preview/pen/xxJNjbN?editors=0010

New website: https://developers.google.com/mediapipe/solutions

While I'll potentially add the new files to our wp.stories.google site, we can use the jsdelivr CDN for now during development.

I hope that the new library is more or less a drop-in replacement with just a slightly different API. If it turns out to be more complicated to switch, we'll have to re-evaluate