Support @defer and @stream

[Type1J]

Is your feature request related to a problem? Please describe.
I'd like to issue 1 request and get back important data, but then have the less important data sent later, or have some parts streamed as they change (like a "like" count).

Describe the solution you'd like
The GraphQL spec is being updated to describe 2 directives: @defer and @stream that were made exactly to solve the problem as described above: graphql/graphql-spec#742 This is different from subscriptions, and it can use http 1.1 chunked encoding without websockets to accomplish this goal as described here: https://youtu.be/icv_Pq06aOY?t=788

Describe alternatives you've considered
Subscriptions are an alternative, however, that requires a second request.

Additional context
These ideas have been around for a long time: https://www.apollographql.com/blog/new-features-in-graphql-batch-defer-stream-live-and-subscribe-7585d0c28b07/

[zaksabeast]

Related to the implementation of @defer and @stream, it looks like @skip and @include have inlined logic at the moment, and I'm curious if there are any thoughts around having a way to provide resolvers for directives.

This could bring a few benefits:

• An established method to add new directives (which would make it easier to add future directives, including @defer and @stream)
• Specific location(s) for directive resolvers to live (if desired)
• A way to add custom directives in the future

[dyedgreen]

An easy way to declare custom directives on types would be really helpful! I was looking into a way to implement @fetchable for some object, and I don't believe there is currently a way to add custom directives at the type level.