4.0.0

• This release introduces a significant functionality change: GraphiQL and GraphiQL Explorer have been removed and replaced with an embedded version of Apollo Studio's Explorer. This means many of the more advanced features of Apollo Studio's Explorer are now available to run against your application's defined GraphQL endpoint, all from the comfort of a browser devtools panel. This change does not require you to have a Studio account and all existing GraphiQL / GraphiQL Explorer functionality has been replicated.
  @mayakoneval in #660