Add Url property to HyperLink; simplify converter link handling; add http/https scheme guard

Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

DiscordChatExporter.Gui/Converters/MarkdownToInlinesConverter.cs

@@ -1,12 +1,9 @@
 using System;
-using System.Diagnostics;
 using System.Globalization;
 using System.Linq;
 using Avalonia.Controls.Documents;
 using Avalonia.Data.Converters;
 using Avalonia.Media;
-using CommunityToolkit.Mvvm.Input;
-using DiscordChatExporter.Gui.Utils.Extensions;
 using DiscordChatExporter.Gui.Views.Controls;
 using Markdig;
 using Markdig.Syntax;
@@ -82,18 +79,16 @@ public class MarkdownToInlinesConverter : IValueConverter
                 break;
             }
 
-            case LinkInline link when link.Url is not null:
+            case LinkInline link when !string.IsNullOrWhiteSpace(link.Url):
             {
-                var text = string.Concat(
-                    link.OfType<LiteralInline>().Select(l => l.Content.ToString())
-                );
-                var url = link.Url;
                 inlines.Add(
                     new InlineUIContainer(
                         new HyperLink
                         {
-                            Text = text,
-                            Command = new RelayCommand(() => Process.StartShellExecute(url)),
+                            Text = string.Concat(
+                                link.OfType<LiteralInline>().Select(l => l.Content.ToString())
+                            ),
+                            Url = link.Url,
                         }
                     )
                 );