refactor(ISignature): create to handle common properties of a signature

- implement to entity and dto

EnvelopeGenerator.Web/Controllers/EnvelopeController.cs

@@ -226,12 +226,18 @@ public class EnvelopeController : ViewControllerBase
         {
             using var pdf = Pdf.FromMemory(doc.ByteData).Design(1, canvas =>
             {
-                canvas.SetStrokeColor(ColorConstants.RED);
-                canvas.SetFillColor(ColorConstants.CYAN);
-                canvas.SetFillColorRgb(222, 220, 215);
-                canvas.SetLineWidth(2);
+                canvas.SetFillColor(new DeviceRgb(135, 62, 35));
+
                 canvas.Rectangle(100, 500, 200, 100);
+
+                canvas.Fill();
+
+                canvas.SetFillColor(new DeviceRgb(222, 220, 215));
+
+                canvas.SetStrokeColor(new DeviceRgb(135, 62, 35));
+                canvas.Circle(300, 500, 100);
                 canvas.FillStroke();
+                canvas.Fill();
             });
 
             doc.ByteData = pdf.ExportAsBytes();