Global ghost hearing (#3954)

* Add global hearing for ghosts

* Fix speech bubbles breaking when out of PVS

Content.Client/Chat/SpeechBubble.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using Content.Client.Interfaces.Chat;
 using Robust.Client.Graphics;
 using Robust.Client.UserInterface;
@@ -110,6 +110,9 @@ namespace Content.Client.Chat
                 _verticalOffsetAchieved = MathHelper.Lerp(_verticalOffsetAchieved, VerticalOffset, 10 * args.DeltaSeconds);
             }
 
+            if (!_senderEntity.Transform.Coordinates.IsValid(_senderEntity.EntityManager))
+                return;
+
             var worldPos = _senderEntity.Transform.WorldPosition;
             worldPos += (0, EntityVerticalOffset);