View message source (#541)

* Added view message source

* Change condition to when button available

Wino.Mail/Dialogs/MessageSourceDialog.xaml.cs

@@ -0,0 +1,24 @@
+using Microsoft.Extensions.DependencyInjection;
+using Windows.UI.Xaml.Controls;
+using Wino.Core.Domain.Interfaces;
+
+
+namespace Wino.Mail.Dialogs
+{
+    public sealed partial class MessageSourceDialog : ContentDialog
+    {
+        private readonly IClipboardService _clipboardService = App.Current.Services.GetService<IClipboardService>();
+        public string MessageSource { get; set; }
+        public bool Copied { get; set; }
+        public MessageSourceDialog()
+        {
+            this.InitializeComponent();
+        }
+
+        private void ContentDialog_PrimaryButtonClick(ContentDialog sender, ContentDialogButtonClickEventArgs args)
+        {
+            _clipboardService.CopyClipboardAsync(MessageSource);
+            Copied = true;
+        }
+    }
+}