Add interfaces for scene authoring (#1466)

Author: Jamie Brynes

workers/unity/Packages/io.improbable.gdk.core/SceneAuthoring.meta

@@ -0,0 +1,27 @@
+using System.Collections.Generic;
+
+namespace Improbable.Gdk.Core.SceneAuthoring
+{
+    public interface IConvertGameObjectToSpatialOsEntity
+    {
+        List<ConvertedEntity> Convert();
+    }
+
+    public readonly struct ConvertedEntity
+    {
+        public readonly EntityId? EntityId;
+        public readonly EntityTemplate Template;
+
+        public ConvertedEntity(EntityId entityId, EntityTemplate template)
+        {
+            EntityId = entityId;
+            Template = template;
+        }
+
+        public ConvertedEntity(EntityTemplate template)
+        {
+            EntityId = null;
+            Template = template;
+        }
+    }
+}

workers/unity/Packages/io.improbable.gdk.core/SceneAuthoring/IConvertGameObjectToSpatialOsEntity.cs

@@ -0,0 +1,7 @@
+namespace Improbable.Gdk.Core.SceneAuthoring
+{
+    public interface ISpatialOsAuthoringComponent
+    {
+        void WriteTo(EntityTemplate template);
+    }
+}