feat: tanks tree mock data

WotBlitzStatisticsPro.Blazor/Helpers/JTokenHelper.cs

@@ -0,0 +1,16 @@
+using Newtonsoft.Json.Linq;
+
+namespace WotBlitzStatisticsPro.Blazor.Helpers
+{
+    public static class JTokenHelper
+    {
+        public static bool IsNullOrEmpty(this JToken token)
+        {
+            return (token == null) ||
+                    (token.Type == JTokenType.Array && !token.HasValues) ||
+                    (token.Type == JTokenType.Object && !token.HasValues) ||
+                    (token.Type == JTokenType.String && token.ToString() == string.Empty) ||
+                    (token.Type == JTokenType.Null);
+        }
+    }
+}