Make the FireworkShapes enum extensible (Closes #9486)

src/main/java/net/minecraftforge/client/FireworkShapeFactoryRegistry.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.client;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.jetbrains.annotations.Nullable;
+
+import net.minecraft.client.particle.FireworkParticles;
+import net.minecraft.world.item.FireworkRocketItem;
+
+/**
+ * Keeps track of custom firework shape types, because Particle is client side only this can't be on the Shape itself.
+ * So sometime during your client initalization call register.
+ */
+public class FireworkShapeFactoryRegistry {
+	private static final Map<FireworkRocketItem.Shape, Factory> factories = new HashMap<>();
+
+	public static interface Factory {
+		void build(FireworkParticles.Starter starter, boolean trail, boolean flicker, int[] colors, int[] fadecolors);
+	}
+
+	public static void register(FireworkRocketItem.Shape shape, Factory factory) {
+		factories.put(shape, factory);
+	}
+
+	@Nullable
+	public static Factory get(FireworkRocketItem.Shape shape) {
+		return factories.get(shape);
+	}
+}