Remove the normalized config export (#4227)
Closes https://github.com/graphql/graphql-js/issues/3853
There's only one normalizedConfig we export and these are just the type
config with a few extras. I would rather than exporting all of them just
stop exporting them for the time being as we don't accept them as inputs
and it can still be derived by doing
`ReturnType<GraphQLInterfaceType['toConfig']>` if it's really needed
