Make Modular Grenades with Chemical payload respect their trigger delay (#39905)

* adds `KeysIn` data field to `ChemicalPayloadComponent`

And check when handling chemical payloads that a trigger key exists.

* Update Content.Server/Payload/EntitySystems/PayloadSystem.cs

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

Content.Shared/Payload/Components/ChemicalPayloadComponent.cs

@@ -1,4 +1,5 @@
 using Content.Shared.Containers.ItemSlots;
+using Content.Shared.Trigger.Systems;
 using Robust.Shared.Serialization;
 
 namespace Content.Shared.Payload.Components;
@@ -14,6 +15,12 @@ public sealed partial class ChemicalPayloadComponent : Component
 
     [DataField("beakerSlotB", required: true)]
     public ItemSlot BeakerSlotB = new();
+
+    /// <summary>
+    /// The keys that will activate the chemical payload.
+    /// </summary>
+    [DataField]
+    public List<string> KeysIn = new() { TriggerSystem.DefaultTriggerKey };
 }
 
 [Serializable, NetSerializable]