Extracts magic strings from Tag calls (#36305)

* Extracts magic strings from Tag calls

When #36281 gets merged, the `TagSystem` methods will all give warnings. Let's fix those warnings before they even happen!

* Adds missing libraries

* Remove not yet implemented TagSystem changes

* Fix tag spelling error

Genuinely surprised there was only 1!

* Styling and proper type changes

* Styling

Co-authored-by: Tayrtahn <tayrtahn@gmail.com>

---------

Co-authored-by: Tayrtahn <tayrtahn@gmail.com>

Content.Server/Payload/EntitySystems/PayloadSystem.cs

@@ -11,6 +11,7 @@ using Robust.Shared.Serialization.Manager;
 using Robust.Shared.Utility;
 using System.Linq;
 using Robust.Server.GameObjects;
+using Robust.Shared.Prototypes;
 
 namespace Content.Server.Payload.EntitySystems;
 
@@ -23,6 +24,8 @@ public sealed class PayloadSystem : EntitySystem
     [Dependency] private readonly IComponentFactory _componentFactory = default!;
     [Dependency] private readonly ISerializationManager _serializationManager = default!;
 
+    private static readonly ProtoId<TagPrototype> PayloadTag = "Payload";
+
     public override void Initialize()
     {
         base.Initialize();
@@ -44,7 +47,7 @@ public sealed class PayloadSystem : EntitySystem
         {
             foreach (var entity in container.ContainedEntities)
             {
-                if (_tagSystem.HasTag(entity, "Payload"))
+                if (_tagSystem.HasTag(entity, PayloadTag))
                     yield return entity;
             }
         }
@@ -71,7 +74,7 @@ public sealed class PayloadSystem : EntitySystem
             return;
 
         // Ensure we don't enter a trigger-loop
-        DebugTools.Assert(!_tagSystem.HasTag(uid, "Payload"));
+        DebugTools.Assert(!_tagSystem.HasTag(uid, PayloadTag));
 
         RaiseLocalEvent(parent, args, false);
     }