Make ReactionResults an array (#34967)

* Make ReactionResults an array

We're making the dictionaries fixed-size anyway.
Alternatively could use a frozendictionary but not sure on the perf difference. Worst case whoever adds another reactionresult makes a minor adjustment

* apply conventions

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Co-authored-by: slarticodefast <161409025+slarticodefast@users.noreply.github.com>

Content.Shared/Atmos/GasMixture.cs

@@ -33,10 +33,9 @@ namespace Content.Shared.Atmos
         public bool Immutable { get; private set; }
 
         [ViewVariables]
-        public readonly Dictionary<GasReaction, float> ReactionResults = new()
+        public readonly float[] ReactionResults =
         {
-            // We initialize the dictionary here.
-            { GasReaction.Fire, 0f }
+            0f,
         };
 
         [ViewVariables]