Implement connection handling for `graphql-transport-ws` sub protocol.

[atsfour]

Fixes #123

It works. I have checked with demo schema on GraphiQL with graphql-ws client.

But some TODOs remain.

In particular, it is better to deal with the handling of the status code later. I'm not good at pedestal.jetty and didn't know how to solve these problems well.

I would also like to add some tests, but I would appreciate any advice on the testing.

[atsfour]

Added some tests. I copied test/com/walmartlabs/lacinia/pedestal/subscriptions_test.clj and fix cases to fit graphql-transport-ws sub protocol.

Also fixed status codes, using Session instance directly.

Any request to fix, I'd like to do it.

[hlship]

I'd like to look at this, but don't know if you've signed the CLA?

[atsfour]

Thanks for considering. And, Yes, I've signed the CLA when past PR was accepted.

https://github.com/walmartlabs/lacinia-pedestal/pull/118

[hlship]

I'm seeing test failures when I build locally.

Testing com.walmartlabs.lacinia.pedestal.subscriptions-graphql-transport-ws-test

FAIL in (client-parallel) (subscriptions_graphql_transport_ws_test.clj:221)
expected: (clojure.core/= {:id right-id, :payload {:data {:ping {:message "right #1"}}}, :type "next"} (com.walmartlabs.lacinia.test-utils/<message!!))
  actual: (not (clojure.core/= {:id 5, :payload {:data {:ping {:message "right #1"}}}, :type "next"} {:type "next", :id 4, :payload {:data {:ping {:message "left #2"}}}}))

FAIL in (client-parallel) (subscriptions_graphql_transport_ws_test.clj:225)
expected: (= 2 (- (clojure.core/deref *ping-subscribes) init-subs))
  actual: (not (= 2 1))

FAIL in (client-parallel) (subscriptions_graphql_transport_ws_test.clj:228)
expected: (clojure.core/= {:id left-id, :payload {:data {:ping {:message "left #2"}}}, :type "next"} (com.walmartlabs.lacinia.test-utils/<message!!))
  actual: (not (clojure.core/= {:id 4, :payload {:data {:ping {:message "left #2"}}}, :type "next"} {:type "next", :id 5, :payload {:data {:ping {:message "right #1"}}}}))

FAIL in (client-parallel) (subscriptions_graphql_transport_ws_test.clj:232)
expected: (clojure.core/= {:id right-id, :payload {:data {:ping {:message "right #2"}}}, :type "next"} (com.walmartlabs.lacinia.test-utils/<message!!))
  actual: (not (clojure.core/= {:id 5, :payload {:data {:ping {:message "right #2"}}}, :type "next"} {:type "complete", :id 4}))

FAIL in (client-parallel) (subscriptions_graphql_transport_ws_test.clj:236)
expected: (clojure.core/= {:id left-id, :type "complete"} (com.walmartlabs.lacinia.test-utils/<message!!))
  actual: (not (clojure.core/= {:id 4, :type "complete"} {:type "next", :id 5, :payload {:data {:ping {:message "right #2"}}}}))

Looks like some kind of off-by-one error on the message ids.

[hlship]

I'm beginning to ramp up towards a milestone release in January; do you have time to look into the above problems?

[hlship]

Getting close to a lacinia 1.2 release, it would be nice to pursue this for a lacinia-pedestal release.