Add plastic sheets chemical recipe (#18865)

* Plasticchemistry

+ Added new way of getting ash: burn oil at 480k and you will get some (1u oil = 1u ash)
+ Added new way of getting plastic: mix together 5 parts oil, 3 parts ash and 2 parts SulfuricAcid to get plastic (10u of mixture = 1 plastic sheet)

* Remove ash recipe

Removed ash recipe because of it's silliness (and because there should be other way of making it)
(https://github.com/space-wizards/space-station-14/pull/18865#issuecomment-1669191528 and https://github.com/space-wizards/space-station-14/pull/18865#issuecomment-1669187894)

Resources/Prototypes/Recipes/Reactions/fun.yml

@@ -90,4 +90,20 @@
     Zinc:
       amount: 1
   products:
-    Licoxide: 1
+    Licoxide: 1
+
+- type: reaction
+  id: PlasticSheet # It's here because "haha look you can get smooth beautiful sheets of plastic from small cylindric beaker" (jokes aside: i dont know where should i put it)
+  impact: Low
+  quantized: true
+  minTemp: 374
+  reactants:
+    Oil:
+      amount: 5
+    Ash:
+      amount: 3
+    SulfuricAcid:
+      amount: 2
+  effects:
+    - !type:CreateEntityReactionEffect
+      entity: SheetPlastic1