Support multiple response types

[mryellow]

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

Unable to properly define response schema's especially in the context of multiple response content-types.

Describe the solution you'd like

The response table should display a response for each content-type.

Valid OpenAPI3 specification:

        "responses": {
          "200": {
            "description": "Foo",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object"
                }
              },
              "application/pdf": {
                "schema": {
                  "type": "string",
                  "format": "binary"
                }
              }
            }
          }
        },

Actual output:

• Note that string is entirely incorrect for any of these response types. https://github.com/Mermade/widdershins/issues/437

|Status|Meaning|Description|Schema|
|---|---|---|---|
|200|[OK](https://tools.ietf.org/html/rfc7231#section-6.3.1)|Foo|string|

Expected output:

|Type|Status|Meaning|Description|Schema|
|---|---|---|---|
|application/json|200|[OK](https://tools.ietf.org/html/rfc7231#section-6.3.1)|Foo|object|
|application/pdf|200|[OK](https://tools.ietf.org/html/rfc7231#section-6.3.1)|Foo|string(binary)|