[graphiql] custom formatting

[mfulton26]

I'd like to be able to specify a custom formatter for GraphiQL (e.g. prettier or something else).

Can we make formatQuery an option to graphiql-react?

[dimaMachina]

Will be possible in next major https://github.com/graphql/graphiql/releases/tag/%40graphiql%2Freact%401.0.0-alpha.4