Log server responses of API bad requests in api_json.log

The API helper render_api_error! previously would log a 400 error with no details in api_json.log, which made it difficult to debug problems in production. To fix this, we need to:

1. Store the intended status code in the request environment. grape-logging doesn't pass this along to the loggers: https://github.com/aserafin/grape_logging/issues/71
2. In the logger, check the code. If it is 400, attach an api_error field that contains the response from the server.

For example:

{
  "time": "2020-04-17T23:59:09.024Z",
  "severity": "INFO",
  <snip>
  "route": "/api/:version/jobs/:id/artifacts",
  "api_error": [
    "{\"message\":\"Validation failed: Invalid file format with specified file type\"}"
  ],
  "correlation_id": "c97d6253-1f92-44d8-91de-b27c1c6d1509"
}

Closes #214879 (closed)