Add graphql-ws support in light of subscriptions-transport-ws deprecation

[bglw]

This was mentioned in #896 but declined at that point. Since then, however, the winds of change have blown in favor of graphql-ws. The graphql-ws protocol differs from Apollo's original subscriptions-transport-ws protocol, and Apollo are soon to archive their protocol and are now recommending use of graphql-ws.

There is already some friction, as graphql-ws-client (and most ws clients coming out) only support the new protocol, while juniper only supports the old.

[tyranron]

@bglw thanks. We have plans to support both versions for the next major release.

[vincenzopalazzo]

@tyranron this feature is landed? :) was thinking that maybe I can be a good mentee? because I would like to have this feature

[tyranron]

@vincenzopalazzo nope, haven't touched it yet. Would like to see a PR from you, if you're willing to. As for design, I think it should be feature-gated in the existing crate. Thanks.

[vincenzopalazzo]

lets see if I can put in my todo list :) there is any channel that can make easy the onboarding on the package?

[tyranron]

@vincenzopalazzo just ask directly in the related PR.