[GUI] Refactor sorting

DiscordChatExporter.Gui/ViewModels/RootViewModel.cs

@@ -150,11 +150,7 @@ namespace DiscordChatExporter.Gui.ViewModels
                 var guildChannelMap = new Dictionary<Guild, IReadOnlyList<Channel>>();
                 await foreach (var guild in discord.GetUserGuildsAsync())
                 {
-                    var channels = await discord.GetGuildChannelsAsync(guild.Id);
+                    guildChannelMap[guild] = await discord.GetGuildChannelsAsync(guild.Id);
-                    guildChannelMap[guild] = channels
-                        .OrderBy(c => c.Category)
-                        .ThenBy(c => c.Name)
-                        .ToArray();
                 }
 
                 GuildChannelMap = guildChannelMap;

DiscordChatExporter.Gui/Views/RootView.xaml

@@ -31,6 +31,7 @@
             </CollectionViewSource.GroupDescriptions>
             <CollectionViewSource.SortDescriptions>
                 <componentModel:SortDescription Direction="Ascending" PropertyName="Category" />
+                <componentModel:SortDescription Direction="Ascending" PropertyName="Name" />
             </CollectionViewSource.SortDescriptions>
         </CollectionViewSource>
     </Window.Resources>