Implement furnace cook speed multiplier API

Signed-off-by: Tassu <git@tassu.me>

paper-api/src/main/java/org/bukkit/block/Furnace.java

@@ -74,6 +74,26 @@ public interface Furnace extends Container {
     @NotNull
     public Map<CookingRecipe<?>, Integer> getRecipesUsed();
 
+    // Paper start
+    /**
+     * Gets the cook speed multiplier that this {@link Furnace} will cook
+     * compared to vanilla.
+     *
+     * @return the multiplier, a value between 0 and 200
+     */
+    public double getCookSpeedMultiplier();
+
+    /**
+     * Sets the speed multiplier that this {@link Furnace} will cook
+     * compared to vanilla.
+     *
+     * @param multiplier the multiplier to set, a value between 0 and 200
+     * @throws IllegalArgumentException if value is less than 0
+     * @throws IllegalArgumentException if value is more than 200
+     */
+    public void setCookSpeedMultiplier(double multiplier);
+    // Paper end
+
     @NotNull
     @Override
     public FurnaceInventory getInventory();