Fix: resolve correct data if schema is wrapped

[ardatan]

If a subschema has the subscription resolvers like below;

{
   Subscription: {
      foo: {
         subscribe: () => someAsyncIteratorReturnsNumber, // not an object with fieldName like { foo: 2 }
         resolve: payload => payload, // << this function gets an object { foo: 2 } if the schema is wrapped, so GraphQL Request fails because returned value here should be a string.
      }
   }
}

So this PR adds additional resolve field to proxy resolvers. It resolves payload[fieldName] by overwriting subschema's resolve method.

[theguild-bot]

The latest changes of this PR are available as alpha in npm: 6.0.5-alpha-fb48136.0

Quickly update your package.json by running:

npx match-version @graphql-tools 6.0.5-alpha-fb48136.0