[3pt]Review openapi schema

[fridex]

Is your feature request related to a problem? Please describe.

As a user of Thoth and a consumer of API endpoints, I would like to have a clear overview of what API endpoints can provide, what are the outputs and responses.

Describe the solution you'd like

Review the openapi schema and unify it, namely:

• check that models are properly documented and are unified
• check that all the return codes are respected and documented in openapi
• make sure the schema is well structured - ex. it has references to the sections and comon inputs, such as page are declared just once
• check that HTTP headers in responses are well documented (ex. paginated responses)

[goern]

/priority important-longterm

[sesheta]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.

If this issue is safe to close now please do so with /close.

/lifecycle stale

[harshad16]

/lifecycle frozen

[harshad16]

/triage accepted
/sig stack-guidance