Finish initial implementation of OpenAPI spec management tools / processes / docs

[matoszz]

This could be a never-ending rabbit hole (especially when you look at trying to walk / wrap some of your code to detect request and response payloads) but our initial implementation should have the minimum included:

• OpenAPI specs generated from the entoas / ogen plugin should lint + be valid
• As much valid $refs as can be programmatically generated out of our REST handlers is completed
• The above specifications are merged, and lint
• The above merged specification has a documentation site generated and published from it

[matoszz]

addressed inside of #956