OAuth2 client's errors don't have enough information when returned by remote party

E.g., when requesting a PD for an unknown scope:

{
  "detail": "failed to retrieve presentation definition: server returned HTTP 400 (expected: 200)",
  "status": 500,
  "title": "RequestServiceAccessToken failed"
}

level=error msg="RequestServiceAccessToken failed" error="failed to retrieve presentation definition: server returned HTTP 400 (expected: 200)" module=Auth/iam operation=RequestServiceAccessToken operationID=RequestServiceAccessToken requestURI="/internal/auth/v2/did:web:api-gateway%3A9443/request-service-access-token" user="<nil>"

But the server logs:

level=warning msg="PresentationDefinition failed" error="invalid_scope - not found" module=Auth/iam operation=PresentationDefinition operationID=PresentationDefinition

This last error should be logged and returned to the client (calling the Nuts node)

Start with the RequestServiceAccessToken and PresentationDefinition operations, using the unknown-scope request shown in the issue to reproduce the failure. Trace how the remote server's "invalid_scope - not found" error is handled; done means that specific error is logged and returned to the Nuts node instead of only reporting HTTP 400.