feat: Add RichTextVideo extension for video playback

[rfgamaral]

Overview

This adds a Video extension to Typist, which is very similar to the one that we have for Images - but for Videos - and parts of the code (mostly related to the uploading mechanism) have been copy-pasted.

Although this was built to be used as an example for a presentation where I go through the steps of building a Typist extension, this could be very well considered ready for prime time. There might be a thing or two that we might want to change and/or do differently, but other than that, the code is pretty much production-ready. However, this will be a draft PR until we are sure that we want to include such extension in our products.

PR Checklist

• Pull request title follows the Conventional Commits Specification
• Added/updated unit test cases and/or end-to-end test cases

Test plan

• Open the preview Storybook deployed to Netlify
• Open the Rich-text → Default story
  • Smoke test the Video extension and make sure it works as you'd expect it to

[netlify]

✅ Deploy Preview for doist-typist ready!

Name	Link
🔨 Latest commit	d5325b9
🔍 Latest deploy log	https://app.netlify.com/sites/doist-typist/deploys/6617acbbab75b10008aa1bf4
😎 Deploy Preview	https://deploy-preview-735--doist-typist.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[rfgamaral]

I'm wondering if this is something that we want to be added to all our editors by default, forcing us to disable this extension for the ones that we don't want to provide support for (e.g., Todoist task name, where we already disable images, along with many others).

The alternative is to remove this from RichTextKit, export it, and let consumers include the extension or not. In other words, make this an optional "bonus" extension.