Add stealthmins (#26263)

* Add stealthmin command.

* Update Content.Server/Administration/Commands/AdminWhoCommand.cs

As suggested by CE.

Co-authored-by: Chief-Engineer <119664036+Chief-Engineer@users.noreply.github.com>

* Add admin notifications for admins toggling stealthmin.

* Localize stealthmin command

---------

Co-authored-by: Chief-Engineer <119664036+Chief-Engineer@users.noreply.github.com>

Content.Shared/Administration/AdminData.cs

@@ -12,6 +12,11 @@ namespace Content.Shared.Administration
         /// </summary>
         public bool Active;
 
+        /// <summary>
+        /// Whether the admin is in stealth mode and won't appear in adminwho to admins without the Stealth flag.
+        /// </summary>
+        public bool Stealth;
+
         /// <summary>
         ///     The admin's title.
         /// </summary>
@@ -56,6 +61,14 @@ namespace Content.Shared.Administration
             return HasFlag(AdminFlags.Admin);
         }
 
+        /// <summary>
+        /// Check if this admin can be hidden and see other hidden admins.
+        /// </summary>
+        public bool CanStealth()
+        {
+            return HasFlag(AdminFlags.Stealth);
+        }
+
         public bool CanAdminReloadPrototypes()
         {
             return HasFlag(AdminFlags.Host);

Content.Shared/Administration/AdminFlags.cs

@@ -94,6 +94,11 @@
         /// </summary>
         MassBan = 1 << 15,
 
+        /// <summary>
+        /// Allows you to remain hidden from adminwho except to other admins with this flag.
+        /// </summary>
+        Stealth = 1 << 16,
+
         /// <summary>
         ///     Dangerous host permissions like scsi.
         /// </summary>