Seal/abstract/virtual everything (#6739)

Content.Client/Chat/ChatHelper.cs

@@ -3,7 +3,7 @@ using Robust.Shared.Maths;
 
 namespace Content.Client.Chat
 {
-    public class ChatHelper
+    public sealed class ChatHelper
     {
         public static Color ChatColor(ChatChannel channel) =>
             channel switch

Content.Client/Chat/StoredChatMessage.cs

@@ -4,7 +4,7 @@ using Robust.Shared.Maths;
 
 namespace Content.Client.Chat
 {
-    public class StoredChatMessage
+    public sealed class StoredChatMessage
     {
         // TODO Make me reflected with respect to MsgChatMessage
 

Content.Client/Chat/UI/ChatBox.xaml.cs

@@ -22,6 +22,7 @@ using Robust.Shared.Utility;
 namespace Content.Client.Chat.UI
 {
     [GenerateTypedNameReferences]
+    [Virtual]
     public partial class ChatBox : Control
     {
         [Dependency] protected readonly IChatManager ChatMgr = default!;

Content.Client/Chat/UI/HudChatBox.cs

@@ -9,7 +9,7 @@ using Robust.Shared.Timing;
 
 namespace Content.Client.Chat.UI
 {
-    public class HudChatBox : ChatBox
+    public sealed class HudChatBox : ChatBox
     {
         // TODO: Revisit the resizing stuff after https://github.com/space-wizards/RobustToolbox/issues/1392 is done,
         // Probably not "supposed" to inject IClyde, but I give up.

Content.Client/Chat/UI/SpeechBubble.cs

@@ -166,7 +166,7 @@ namespace Content.Client.Chat.UI
         }
     }
 
-    public class TextSpeechBubble : SpeechBubble
+    public sealed class TextSpeechBubble : SpeechBubble
 
     {
         public TextSpeechBubble(string text, EntityUid senderEntity, IEyeManager eyeManager, IChatManager chatManager, IEntityManager entityManager, string speechStyleClass)