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.IntegrationTests/Tests/Commands/SuicideCommandTests.cs

@@ -1,4 +1,4 @@
-using System.Linq;
+using System.Linq;
 using Content.Shared.Damage;
 using Content.Shared.Damage.Prototypes;
 using Content.Shared.Execution;
@@ -52,7 +52,7 @@ public sealed class SuicideCommandTests
   name: test version of the material reclaimer
   components:
   - type: MaterialReclaimer";
-
+    private static readonly ProtoId<TagPrototype> CannotSuicideTag = "CannotSuicide";
     /// <summary>
     /// Run the suicide command in the console
     /// Should successfully kill the player and ghost them
@@ -201,7 +201,7 @@ public sealed class SuicideCommandTests
             mobStateComp = entManager.GetComponent<MobStateComponent>(player);
         });
 
-        tagSystem.AddTag(player, "CannotSuicide");
+        tagSystem.AddTag(player, CannotSuicideTag);
 
         // Check that running the suicide command kills the player
         // and properly ghosts them without them being able to return to their body