Fix GraalVM reflection metadata for GraphQL client

Prior to this commit, the embedded reachability metadata for GraalVM
would declare a reflection hint for `GraphQlWebSocketMessage` when the
RSocket or WebSocket clients are reachable.
The `CodecDelegate` relies on this message class to test codecs and
detect a JSON-capable instance. This is true for all supported
GraphQlClient implementations.

This commit revisits the embedded reachability metadata to:

* allow reflection on `GraphQlWebSocketMessage` if any client extending
  `AbstractGraphQlClientBuilder` is available
* allow reflection on `GraphQlWebSocketMessage` if a
  `GraphQlWebSocketHandler` is reachable

Fixes gh-825

Author: bclozel

spring-graphql/src/main/resources/META-INF/native-image/org.springframework.graphql/spring-graphql/reflect-config.json

@@ -12,7 +12,7 @@
     "allDeclaredMethods":true,
     "allDeclaredConstructors":true,
     "condition": {
-      "typeReachable": "org.springframework.graphql.client.DefaultRSocketGraphQlClientBuilder"
+      "typeReachable": "org.springframework.graphql.client.AbstractGraphQlClientBuilder"
     }
   },
   {
@@ -21,7 +21,7 @@
     "allDeclaredMethods":true,
     "allDeclaredConstructors":true,
     "condition": {
-      "typeReachable": "org.springframework.graphql.client.DefaultWebSocketGraphQlClientBuilder"
+      "typeReachable": "org.springframework.graphql.server.webflux.GraphQlWebSocketHandler"
     }
   }
 ]