add LdtkFieldInstance and LdtkEntityMap classes; update LdtkSceneBuilder to support entity mapping

addons/csharp_ldtk_importer/Models/LdtkEntityInstance.cs

@@ -9,4 +9,7 @@ public class LdtkEntityInstance
 
     [JsonPropertyName("px")]
     public int[] Px { get; set; }
+    
+    [JsonPropertyName("fieldInstances")]
+    public LdtkFieldInstance[] FieldInstances { get; set; }
 }

addons/csharp_ldtk_importer/Models/LdtkFieldInstance.cs

@@ -0,0 +1,16 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace CSharpLdtkImporter.Models;
+
+public class LdtkFieldInstance
+{
+    [JsonPropertyName("__identifier")]
+    public string Identifier { get; set; }
+
+    [JsonPropertyName("__type")]
+    public string Type { get; set; }
+
+    [JsonPropertyName("__value")]
+    public JsonElement Value { get; set; }
+}

addons/csharp_ldtk_importer/Models/LdtkFieldInstance.cs.uid

@@ -0,0 +1 @@
+uid://dgwt3rdvkdypq