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/frmEnvelopeEditor.vb

@@ -18,7 +18,7 @@ Imports EnvelopeGenerator.Domain.Entities
 Partial Public Class frmEnvelopeEditor
     Public Property Envelope As Envelope
     Public Property Documents As New BindingList(Of EnvelopeDocument)
-    Public Property Receivers As New BindingList(Of Receiver)
+    Public Property Receivers As New BindingList(Of ReceiverVM)
 
     Private AllReceiverEmails As New List(Of String)
 
@@ -105,7 +105,7 @@ Partial Public Class frmEnvelopeEditor
         Else
             Controller = New EnvelopeEditorController(State, Envelope)
             Documents = New BindingList(Of EnvelopeDocument)(Controller.Envelope.Documents)
-            Receivers = New BindingList(Of Receiver)(Controller.Envelope.Receivers)
+            Receivers = New BindingList(Of ReceiverVM)(Controller.Envelope.Receivers.Select(Function(r) ReceiverVM.From(r)).ToList())
 
             For Each docItem As EnvelopeDocument In Documents
                 If Not File.Exists(docItem.Filepath) Then
@@ -233,7 +233,7 @@ Partial Public Class frmEnvelopeEditor
                         .Document = Controller.Envelope.Documents.
                             Where(Function(d) d.Filename = oDocument.Filename).
                             SingleOrDefault(),
-                        .Receivers = Controller.Envelope.Receivers.ToList
+                        .Receivers = Controller.Envelope.Receivers.Select(Function(r) ReceiverVM.From(r)).ToList()
                     }
                 oForm.ShowDialog()
 
@@ -335,7 +335,7 @@ Partial Public Class frmEnvelopeEditor
 
 
 
-        If Controller.SaveReceivers(oEnvelope, Receivers.ToList) = False Then
+        If Controller.SaveReceivers(oEnvelope, Receivers.Select(Function(vm) vm.Receiver).ToList()) = False Then
             MsgBox(Resources.Envelope.Error_when_saving_the_recipients, MsgBoxStyle.Critical, Text)
             Return False
         End If
@@ -459,7 +459,7 @@ Partial Public Class frmEnvelopeEditor
     End Sub
 
     Private Sub ViewReceivers_InitNewRow(sender As Object, e As InitNewRowEventArgs) Handles ViewReceivers.InitNewRow
-        Dim oReceiver As Receiver = ViewReceivers.GetRow(e.RowHandle)
+        Dim oReceiver As ReceiverVM = ViewReceivers.GetRow(e.RowHandle)
 
         Dim oUsedColors = Receivers.Select(Of Integer)(Function(r) r.ColorType).ToList()
         Dim oAllColors = [Enum].GetValues(GetType(Domain.Constants.ColorType)).Cast(Of Integer).ToList()