Modify admin chat (#13050)

* split admin chat into new channel

* add ability to play audio when a chat message is received and add audio to admin chat

* give client control of AdminChat sound and volume + suppress sound for senders

Content.Client/UserInterface/Systems/Chat/Widgets/ChatBox.xaml.cs

@@ -7,7 +7,9 @@ using Robust.Client.AutoGenerated;
 using Robust.Client.UserInterface;
 using Robust.Client.UserInterface.Controls;
 using Robust.Client.UserInterface.XAML;
+using Robust.Shared.Audio;
 using Robust.Shared.Input;
+using Robust.Shared.Player;
 using Robust.Shared.Utility;
 using static Robust.Client.UserInterface.Controls.LineEdit;
 
@@ -52,6 +54,9 @@ public partial class ChatBox : UIWidget
             return;
         }
 
+        if (msg is { Read: false, AudioPath: { } })
+            SoundSystem.Play(msg.AudioPath, Filter.Local(), new AudioParams().WithVolume(msg.AudioVolume));
+
         msg.Read = true;
 
         var color = msg.MessageColorOverride != null