[studio] Allow editors to comment

[oliviertassinari]

Summary 💡

Make it possible for the rest of the team to leave comments on the UI being built.

Examples 🌈

• Figma https://www.figma.com/blog/stay-in-the-flow-with-redesigned-comments/

• Tooljet https://app.tooljet.com/

• https://app.appsmith.com/

• In Webflow, no one seems to care: https://wishlist.webflow.com/ideas/WEBFLOW-I-4949
• Retool doesn't have this feature, maybe it doesn't matter? People that needs collaboration want Source control with GitHub #389 and then they comment on GitHub.
• Bubble.io, doesn't have this feature, wow surprising.

Motivation 🔦

This feature is most useful for teams that decide not to work on a GitHub first workflow #389, with a master branch and PRs.

With @newguy-123 we have tried to use https://www.plasmic.app/ for the first iteration of the landing page of MUI Toolpad (cc @chungwu). However, we quickly realized that we would need to be able to leave comments on the design. In the end, we have decided to approach the problem a bit differently. Prakhar (PM) is first going to use Figma to iterate on feedback, and then, maybe use pro-code to ship the new landing page to production. Once our new designer joins, she can iterate on a second version of the landing page for production.