Use order-preserving JSON encoder in graphql-server

This uses the GraphQLJSONEncoder when converting a GraphQLResult to a
Response to return the query results in the order that the were
specified in the request.

graphql-server/Sources/App/GraphQL/GraphQL+ResponseGenerator.swift

@@ -0,0 +1,18 @@
+import GraphQL
+import HTTPTypes
+import Hummingbird
+
+extension GraphQLResult: ResponseGenerator {
+    public func response(from _: Request, context _: some RequestContext) throws -> Response {
+        let encoder = GraphQLJSONEncoder()
+        let data = try encoder.encode(self)
+        return Response(
+            status: .ok,
+            headers: [
+                .contentType: "application/json; charset=utf-8",
+                .contentLength: "\(data.count)",
+            ],
+            body: .init(byteBuffer: ByteBuffer(data: data))
+        )
+    }
+}

graphql-server/Sources/App/GraphQL/GraphQLError+HBError.swift → graphql-server/Sources/App/GraphQL/GraphQLError+HTTPResponseError.swift

@@ -19,6 +19,6 @@ extension GraphQLError: HTTPResponseError {
     }
 
     public func response(from request: Request, context: some RequestContext) -> Response {
-        .init(status: status, headers: headers, body: .init(byteBuffer: ByteBuffer(string: message)))
+        .init(status: self.status, headers: self.headers, body: .init(byteBuffer: ByteBuffer(string: message)))
     }
 }