Dynamically determine endpointResources

[razor-x]

Instead of using this: https://github.com/seamapi/javascript-http/blob/main/generate-routes.ts#L76
Use x-fern-sdk-return-value

Currently this exists in the openapi metadata as x-fern-sdk-return-value. This should instead be normalized to x-response-key to match the SDK (It is not a "fern thing" it's a Seam API thing):

javascript-http/src/lib/seam/connect/seam-http-request.ts

Line 19 in 65021e4

readonly responseKey: TResponseKey

Fixing the key name is out of scope of this issue, but the value should be isolated to a constant, like

const openapiResponseKeyProp = 'x-fern-sdk-return-value'