Ghost roles create new minds, better tracking of roles at round end screen (#5175)

* Ghost roles now get new Minds

* Some round start/end button stuff

* Mind tracking for better round end reports

* Make traitor kill objectives use mind CharacterName rather than actual occupied entity ("kill brain" prevention)

* Transition over to EntityUid for mind stuff because that's the only way to do it

* BrainSystem fix for PR rebase

Content.Server/Ghost/ObserverRole.cs

@@ -0,0 +1,18 @@
+using Content.Server.Roles;
+using Robust.Shared.Localization;
+
+namespace Content.Server.Ghost
+{
+    /// <summary>
+    /// This is used to mark Observers properly, as they get Minds
+    /// </summary>
+    public class ObserverRole : Role
+    {
+        public override string Name => Loc.GetString("observer-role-name");
+        public override bool Antagonist => false;
+
+        public ObserverRole(Mind.Mind mind) : base(mind)
+        {
+        }
+    }
+}