Add reaction randomization. (#308)

* Add random products datafield to the reaciton prototype.

One of the items in the list will be used as additional products as a
result of the reaction and will be persistent per round.

Resolves #245

* Another try

Add getter and setter for the reaction products field and
add random products there.

* There is no such product as CP14BasicEffectHealHeat

* Try to visualize random products in the guidebook

* experimental recipes

* fix

* file restructurization

* Guidebook alchemy update

* Update Alchemy.xml

* fix

* Update mixing_simple.yml

---------

Co-authored-by: Ed <96445749+TheShuEd@users.noreply.github.com>

Content.Server/_CP14/Alchemy/EntitySystems/CP14RandomReagentReactionsSystem.cs

@@ -0,0 +1,26 @@
+using Content.Server.GameTicking.Events;
+using Content.Shared.Chemistry.Reaction;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Random;
+
+namespace Content.Server._CP14.Alchemy.EntitySystems;
+
+public sealed class CP14RandomReagentReactionsSystem : EntitySystem
+{
+    [Dependency] private readonly IPrototypeManager _proto = default!;
+    [Dependency] private readonly IRobustRandom _random = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<RoundStartingEvent>(OnRoundStart);
+    }
+
+    private void OnRoundStart(RoundStartingEvent ev)
+    {
+        foreach (var reaction in _proto.EnumeratePrototypes<ReactionPrototype>())
+        {
+            reaction.Cp14RandomProductIndex = _random.Next(reaction.Cp14RandomProducts.Count);
+        }
+    }
+}