Add chat.max_announcement_length cvar (#23571)

* Add announce message length to UI and make a cvar for it

* Update comm console server-side trim to use the cvar

* Rely on the new OnTextChanged event

Because OnKeyBindUp only works for keys that have binds

* Add a similar indicator to nukies' war declaration UI

* Remove message length indicators for now cuz it requires the engine update

* Rename cvar slightly

* Refactor duplicated code to a helper method

* Remove message trimming from *Window class as it's better to live in the BoundUserInterface where the other message handling happens

* Rename to chat.max_announcement_length

Content.Client/Communications/UI/CommunicationsConsoleMenu.xaml.cs

@@ -23,7 +23,7 @@ namespace Content.Client.Communications.UI
             var loc = IoCManager.Resolve<ILocalizationManager>();
             MessageInput.Placeholder = new Rope.Leaf(loc.GetString("comms-console-menu-announcement-placeholder"));
 
-            AnnounceButton.OnPressed += (_) => Owner.AnnounceButtonPressed(Rope.Collapse(MessageInput.TextRope).Trim());
+            AnnounceButton.OnPressed += (_) => Owner.AnnounceButtonPressed(Rope.Collapse(MessageInput.TextRope));
             AnnounceButton.Disabled = !owner.CanAnnounce;
 
             AlertLevelButton.OnItemSelected += args =>