Reactive 3.0 (#5443)

* probably scrapping this

* reimpl old behavior

* misc fixes and initial yaml

* works basically first try

Content.Server/Chemistry/Components/SmokeSolutionAreaEffectComponent.cs

@@ -37,7 +37,7 @@ namespace Content.Server.Chemistry.Components
                 internals.AreInternalsWorking())
                 return;
 
-            var chemistry = EntitySystem.Get<ChemistrySystem>();
+            var chemistry = EntitySystem.Get<ReactiveSystem>();
             var cloneSolution = solution.Clone();
             var transferAmount = FixedPoint2.Min(cloneSolution.TotalVolume * solutionFraction, bloodstream.EmptyVolume);
             var transferSolution = cloneSolution.SplitSolution(transferAmount);