Add import of polygon from dxf

StructureHelperCommon/Services/Exports/IGetDxfLayerLogic.cs

@@ -0,0 +1,12 @@
+using netDxf;
+using netDxf.Tables;
+
+namespace StructureHelperCommon.Services.Exports
+{
+    public interface IGetDxfLayerLogic
+    {
+        AciColor GetLayerColor(LayerNames layerName);
+        string GetLayerName(LayerNames layerName);
+        Layer GetOrCreateLayer(DxfDocument dxf, LayerNames layerName);
+    }
+}