refactor(pdf-burner): replace annotation type constants with AnnotationType class

- Removed individual annotation type constants (ANNOTATION_TYPE_IMAGE, ANNOTATION_TYPE_INK, ANNOTATION_TYPE_WIDGET)
- Introduced new Friend Class `AnnotationType` to encapsulate annotation type string constants
- Updated all references to use `AnnotationType.Image`, `AnnotationType.Ink`, and `AnnotationType.Widget`
- Improved code organization by grouping related constants and removing redundant declarations

EnvelopeGenerator.CommonServices/Jobs/FinalizeDocument/PDFBurner.vb

@@ -20,9 +20,6 @@ Namespace Jobs.FinalizeDocument
         Private ReadOnly Manager As AnnotationManager
         Private ReadOnly LicenseManager As LicenseManager
 
-        Private Const ANNOTATION_TYPE_IMAGE = "pspdfkit/image"
-        Private Const ANNOTATION_TYPE_INK = "pspdfkit/ink"
-        Private Const ANNOTATION_TYPE_WIDGET = "pspdfkit/widget"
         Private Property _pdfBurnerParams As PDFBurnerParams
 
         Public Sub New(pLogConfig As LogConfig, pGDPictureLicenseKey As String, pdfBurnerParams As PDFBurnerParams)
@@ -106,16 +103,13 @@ Namespace Jobs.FinalizeDocument
                 Logger.Debug("Adding AnnotationID: " + oAnnotation.id)
 
                 Select Case oAnnotation.type
-                    Case ANNOTATION_TYPE_IMAGE
+                    Case AnnotationType.Image
-
                         AddImageAnnotation(oAnnotation, oAnnotationData.attachments)
                         Exit Select
-
+                    Case AnnotationType.Ink
-                    Case ANNOTATION_TYPE_INK
                         AddInkAnnotation(oAnnotation)
                         Exit Select
-
+                    Case AnnotationType.Widget
-                    Case ANNOTATION_TYPE_WIDGET
                         'Add form field values
                         Dim formFieldValue = oAnnotationData.formFieldValues.FirstOrDefault(Function(fv) fv.name = oAnnotation.id)
                         If formFieldValue IsNot Nothing AndAlso Not _pdfBurnerParams.IgnoredLabels.Contains(formFieldValue.value) Then
@@ -196,6 +190,12 @@ Namespace Jobs.FinalizeDocument
 #End Region
 
 #Region "Model"
+        Friend Class AnnotationType
+            Public Const Image As String = "pspdfkit/image"
+            Public Const Ink As String = "pspdfkit/ink"
+            Public Const Widget As String = "pspdfkit/widget"
+        End Class
+
         Friend Class AnnotationData
             Public Property annotations As List(Of Annotation)