includes deadmined admins in adminsystem playerlist updates

Content.Server/Administration/Managers/IAdminManager.cs

@@ -24,6 +24,11 @@ namespace Content.Server.Administration.Managers
         /// </remarks>
         IEnumerable<IPlayerSession> ActiveAdmins { get; }
 
+        /// <summary>
+        /// Gets all admins currently on the server, even de-adminned ones.
+        /// </summary>
+        IEnumerable<IPlayerSession> AllAdmins { get; }
+
         /// <summary>
         ///     Checks if a player is an admin.
         /// </summary>