Adding custom blocks and ability to add them to pages

[fyrepenguin]

We can give users the ability to build their own blocks like subscription forms, custom banners, custom scripts or html that can be used in multiple posts or pages.

[deshetti]

This might be worth checking to see if we could implement it according to their spec:

Intro: https://blockprotocol.org/
Specification: https://blockprotocol.org/spec
Developing Blocks: https://blockprotocol.org/docs/developing-blocks#the-quickest-start