PUT/POST AnyBlock instead of a markdown body

[zetashift]

Have you read a contributing guide?

• I have read CONTRIBUTING.md
• I have searched the existing requests and didn't find any that were similar
• I have considered creating a pull request instead and want to proceed

Clear and concise description of the problem

Currently one submits strings containing markdown to the API. It would be nice if it supported AnyBlock structures as well.

Suggested solution

I'm not sure what's needed here to solve this, so I also can't really suggest an useful solution.

Alternative

Markdown currently as-is works fine, it's limited in the markdown features though and more involved blocks can't be created.

Additional context

No response