Add admin alerts (#13589)

Content.Shared/Chat/ChatChannel.cs

@@ -64,15 +64,20 @@ namespace Content.Shared.Chat
         /// </summary>
         Admin = 1 << 10,
 
+        /// <summary>
+        ///     Admin alerts, messages likely of elevated importance to admins
+        /// </summary>
+        AdminAlert = 1 << 11,
+
         /// <summary>
         ///     Admin chat
         /// </summary>
-        AdminChat = 1 << 11,
+        AdminChat = 1 << 12,
 
         /// <summary>
         ///     Unspecified.
         /// </summary>
-        Unspecified = 1 << 12,
+        Unspecified = 1 << 13,
 
         /// <summary>
         ///     Channels considered to be IC.

Content.Shared/Chat/ChatChannelExtensions.cs

@@ -12,6 +12,7 @@ public static class ChatChannelExtensions
             ChatChannel.OOC => Color.LightSkyBlue,
             ChatChannel.Dead => Color.MediumPurple,
             ChatChannel.Admin => Color.Red,
+            ChatChannel.AdminAlert => Color.Red,
             ChatChannel.AdminChat => Color.HotPink,
             ChatChannel.Whisper => Color.DarkGray,
             _ => Color.LightGray