SPIGOT-5121: Method to set PierceLevel of arrows

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/entity/AbstractArrow.java

@@ -43,6 +43,22 @@ public interface AbstractArrow extends Projectile {
      */
     public void setDamage(double damage);
 
+    /**
+     * Gets the number of times this arrow can pierce through an entity.
+     *
+     * @return pierce level
+     */
+    public int getPierceLevel();
+
+    /**
+     * Sets the number of times this arrow can pierce through an entity.
+     *
+     * Must be between 0 and 127 times.
+     *
+     * @param pierceLevel new pierce level
+     */
+    public void setPierceLevel(int pierceLevel);
+
     /**
      * Gets whether this arrow is critical.
      * <p>