[API] Convert to OpenAPI

[Fryguy]

• [x] Load models to build schema
• [x] Add descriptions if a column has a comment
• [ ] Detect and build parameters
• [ ] Handle multiple post actions
• [ ] Run as a GHA on a schedule to keep schema up to date
• [ ] Run on API PRs to detect new/updates/deleted paths/parameters

[abellotti]

We may want the OpenAPI spec versioning to match ManageIQ's, bringing in the API & MiQ versioning that were on separate version paths to now being one in the same.