Summary: Adds a custom interactive Swagger API console at `/apiconsole`. For now, this isn't visibly linked anywhere.
Test Plan: Manual, this is still an experimental and private feature. The idea is to merge this soon so that we have a chance to try it out in production.
Reviewers: georgegevoian
Reviewed By: georgegevoian
Differential Revision: https://phab.getgrist.com/D4151
