Consider hosting Cloud API docs in the Prefect docs

[discdiver]

First check

• [X] I added a descriptive title to this issue.
• [X] I used GitHub search to find a similar request and didn't find it 😇

Describe the issue

Cloud API docs are currently built with redocly, hosted on Cloud

Describe the proposed change

Build with Mintlify and host alongside the Prefect self-hosted server docs.

Additional context

cc: @WillRaphaelson, @danielhstahl, @znicholasbrown