Revert "chore: Remove playroom, since even the latest version (0.23.0) has a peer-dep on React 16.x which conflicts with PRC’s peer-dep on React 17.x"

This reverts commit e3612051ab01bf1dfbdf477f00ef96b0ea8aca47.

Storybook has the same issue (storybookjs/storybook#14119, storybookjs/storybook#14619), so if we’re open to using '--legacy-peer-deps' to use Storybook, we can’t justify removing Playroom on anti-'--legacy-peer-deps' grounds.

Author: smockle