message: [now-cli] Add the `x-vercel-id` and `x-vercel-cache` response headers to `now dev`
  Matches current production.
diff: @@ -1060,6 +1060,8 @@ export default class DevServer {
  'x-now-trace': 'dev1',
  'x-now-id': nowRequestId,
  'x-now-cache': 'MISS',
  + 'x-vercel-id': nowRequestId,
  + 'x-vercel-cache': 'MISS',
  };
  for (const [name, value] of Object.entries(allHeaders)) {
  res.setHeader(name, value);
  