Newer versions of Graphiql [support headers in the editor](https://github.com/graphql/graphiql/pull/1543), but it looks like the version of Graphiql in `absinthe_plug` doesn't have it.
Newer versions of Graphiql support headers in the editor, but it looks like the version of Graphiql in
absinthe_plugdoesn't have it.