Option to rename `requestBody`

[gersongoulart]

In the OpenAPI v3 spec, the requestBody does not have a name. By default, it will be passed into the generated function as requestBody.

It would be nice to accept the commonly used x-body-name property in the operation schema to override this name.

Example:

paths:
  /foo:
    post:
      operationId: api.foo_get
      requestBody:
        x-body-name: payload
        content:
          application/json:
            schema:
              ...

# default
body: requestBody,

# based on x-body-name
body: payload,

[mrlubos]

Hey @gersongoulart, I see you have other commits in your fork in addition to this feature, but just wanted to let you know I've also added this feature to our fork. It has some other features too, mostly around OpenAPI 3.1 compatibility