Player post-spawn hook and player ghosting controlled by preset (#2734)

* GamePreset: Add a hook to catch all player spawns for modification.

Unless someone makes the entire job system unpluggable, this is what you get...

* GamePreset: Is now in control of voluntary ghosting

* Clean up ghost code to only rely on a player's Mind

Content.Server/Interfaces/GameTicking/IGameTicker.cs

@@ -1,8 +1,10 @@
 using System;
 using System.Collections.Generic;
 using Content.Server.GameTicking;
+using Content.Server.Mobs;
 using Content.Shared.Roles;
 using Robust.Server.Interfaces.Player;
+using Robust.Server.Interfaces.Console;
 using Robust.Shared.Interfaces.GameObjects;
 using Robust.Shared.Map;
 using Robust.Shared.Timing;
@@ -42,6 +44,9 @@ namespace Content.Server.Interfaces.GameTicking
         void ToggleReady(IPlayerSession player, bool ready);
         void ToggleDisallowLateJoin(bool disallowLateJoin);
 
+        /// <summary>proxy to GamePreset (actual handler)</summary>
+        bool OnGhostAttempt(Mind mind, bool canReturnGlobal);
+
         EntityCoordinates GetLateJoinSpawnPoint();
         EntityCoordinates GetJobSpawnPoint(string jobId);
         EntityCoordinates GetObserverSpawnPoint();