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

• [x] Pull request title follows the Conventional Commits Specification
• [x] 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

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