Implement Firework.detonate(). Adds BUKKIT-4538

This implements the detonate method from bukkit by setting the fuse
timer to 0. This makes a firework explode using the normal codepath,
but without waiting for the fuse.

src/main/java/org/bukkit/craftbukkit/entity/CraftFirework.java

@@ -47,14 +47,17 @@ public class CraftFirework extends CraftEntity implements Firework {
         return "CraftFirework";
     }
 
+    @Override
     public EntityType getType() {
         return EntityType.FIREWORK;
     }
 
+    @Override
     public FireworkMeta getFireworkMeta() {
         return (FireworkMeta) item.getItemMeta();
     }
 
+    @Override
     public void setFireworkMeta(FireworkMeta meta) {
         item.setItemMeta(meta);
 
@@ -63,4 +66,9 @@ public class CraftFirework extends CraftEntity implements Firework {
 
         getHandle().getDataWatcher().h(FIREWORK_ITEM_INDEX); // Update
     }
+
+    @Override
+    public void detonate() {
+        getHandle().expectedLifespan = 0;
+    }
 }