[grid] Adding node count to GraphQL data

Author: diemol

java/server/src/org/openqa/selenium/grid/graphql/Grid.java

@@ -98,6 +98,10 @@ public List<Node> getNodes() {
     return toReturn.build();
   }
 
+  public int getNodeCount() {
+    return distributorStatus.get().getNodes().size();
+  }
+
   public int getSessionCount() {
     return distributorStatus.get().getNodes().stream()
       .map(NodeStatus::getSlots)

java/server/src/org/openqa/selenium/grid/graphql/selenium-grid-schema.graphqls

@@ -65,6 +65,7 @@ type GridQuery {
 type Grid {
   uri: Uri!
   totalSlots: Int!
+  nodeCount: Int!
   maxSession: Int!
   sessionCount: Int!
   version: String!