SPIGOT-5380, SPIGOT-6958, #772: Add some missing entity API

By: Ollie <69084614+olijeffers0n@users.noreply.github.com>

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

@@ -3,4 +3,19 @@ package org.bukkit.entity;
 /**
  * Represents a turtle.
  */
-public interface Turtle extends Animals { }
+public interface Turtle extends Animals {
+
+    /**
+     * Gets whether the turtle has an egg
+     *
+     * @return Whether the turtle has an egg
+     */
+    boolean hasEgg();
+
+    /**
+     * Gets whether the turtle is laying an egg
+     *
+     * @return Whether the turtle is laying an egg
+     */
+    boolean isLayingEgg();
+}