Refactor receiver handling and update solution structure

- Updated `BaseController.vb` to use `Receiver.Id` for deletion.
- Changed `Receivers` property in `frmEnvelopeEditor.vb` to `BindingList(Of ReceiverVM)` and adjusted initialization and usage throughout the file.
- Modified `frmFieldEditor.vb` to use `List(Of ReceiverVM)` for receivers and updated related methods.
- Adjusted color assignment logic in `frmMain.vb` to utilize a new `Value` class.
- Added new project for `EnvelopeGenerator.Form` in the solution file.
- Introduced new enums `ContractType` and `PageOrientation` in their respective files.

EnvelopeGenerator.Form/frmFieldEditor.vb

@@ -19,8 +19,8 @@ Partial Public Class frmFieldEditor
     Private Controller As FieldEditorController
 
     Public Property Document As EnvelopeDocument = Nothing
-    Public Property Receivers As List(Of Receiver)
-    Public Property SelectedReceiver As Receiver = Nothing
+    Public Property Receivers As List(Of ReceiverVM)
+    Public Property SelectedReceiver As ReceiverVM = Nothing
 
     Private UnsavedChanges As Boolean = False
 
@@ -106,7 +106,7 @@ Partial Public Class frmFieldEditor
         UnsavedChanges = True
     End Sub
 
-    Private Function CreateBarItem(pReceiver As Receiver) As BarItem
+    Private Function CreateBarItem(pReceiver As ReceiverVM) As BarItem
         Dim oItem = New BarButtonItem(BarManager1, pReceiver.Name)
         Dim oBaseCircle As SvgImage = SvgImageCollection1.Item(0)
         Dim oColorCircle = Helpers.GetColorCircle(oBaseCircle, pReceiver.Color)
@@ -121,7 +121,7 @@ Partial Public Class frmFieldEditor
     Private Sub ReceiverItem_Click(sender As Object, e As ItemClickEventArgs)
         Me.SuspendLayout()
 
-        Dim oSelectedReceiver As Receiver = e.Item.Tag
+        Dim oSelectedReceiver As ReceiverVM = e.Item.Tag
         Dim oCurrentPage = GDViewer.CurrentPage
         Dim oCurrentPosition = GDViewer.GetVScrollBarPosition()
 
@@ -153,7 +153,7 @@ Partial Public Class frmFieldEditor
         Me.ResumeLayout()
     End Sub
 
-    Private Sub SetReceiver(pReceiver As Receiver)
+    Private Sub SetReceiver(pReceiver As ReceiverVM)
         Dim oBaseCircle As SvgImage = SvgImageCollection1.Item(0)
 
         txtReceiver.Caption = pReceiver.Name
@@ -435,6 +435,4 @@ Partial Public Class frmFieldEditor
             End Select
         End If
     End Sub
-End Class
-
-
+End Class