Add EntityToggleSwimEvent and isSwimming / setSwimming API

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

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

@@ -325,6 +325,22 @@ public interface LivingEntity extends Attributable, Entity, Damageable, Projecti
      */
     public void setGliding(boolean gliding);
 
+    /**
+     * Checks to see if an entity is swimming.
+     *
+     * @return True if this entity is swimming.
+     */
+    public boolean isSwimming();
+
+    /**
+     * Makes entity start or stop swimming.
+     *
+     * This may have unexpected results if the entity is not in water.
+     *
+     * @param swimming True if the entity is swimming.
+     */
+    public void setSwimming(boolean swimming);
+
     /**
      * Sets whether an entity will have AI.
      *