adds endpoint-specific transforms

[thorhj]

Addressing #749

Checklist

• [x] run npm run test and npm run benchmark
• [x] tests and/or benchmarks are included
• [x] documentation is changed or added
• [x] commit message and code follows the Developer's Certification of Origin and the Code of conduct

[thorhj]

Two considerations for the reviewer:

1. The property for the transform function is called swaggerTransform but supports both OpenAPI and Swagger specs of course. Don't know if that is confusion and a better name should be added (or two separate properties).
2. The implementation allows the swaggerTransform to be given the value null which has its own specific meaning. Maybe this should be the string literal "disable" or something else to be more clear.

[thorhj]

missing typing tests.

Added some tests in types.test.ts. Let me know if they should be written differently, haven't made such tests before (I'm usually working in Typescript directly 😉)

[thorhj]

I reviewed it now.

swggerTransform null is quiet unintuitive. I would personally prefer false for deactivating.

I agree, changed it to false instead of null.

[fredrikj31]

When is this set to be released? 🤔

[mcollina]

done now