Big queries lead to big Request header size due to Referrer

As graphiql adds the query to the address bar, and this url gets added as referer header to the POST request to the graphql endpoint, the request header gets to big for big queries and the request fails.

Proposal: add `referrerPolicy: "no-referrer"` to default fetcher to circumvent this issue

cf. https://hacks.mozilla.org/2016/03/referrer-and-cache-control-apis-for-fetch/