Support a structure similar to express-openapi

[rpcope1]

I really like how express-openapi allows you to put your data structure definitions and security definitions in one place, and then place the swagger specification for the routes themselves together with the route implementation. It would be nice to do something similar with this (instead of having one massive Swagger file).

Items to do:

• Can this be done nicely with what's already here, without major modifications?
• Can this be done in a relatively Pythonic way?
• Proof of Concept