SPIGOT-4753: Add Pose API

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

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

@@ -0,0 +1,37 @@
+package org.bukkit.entity;
+
+/**
+ * Represents an entity body pose.
+ */
+public enum Pose {
+
+    /**
+     * Entity is standing normally.
+     *
+     */
+    STANDING,
+    /**
+     * Entity is gliding.
+     */
+    FALL_FLYING,
+    /**
+     * Entity is sleeping.
+     */
+    SLEEPING,
+    /**
+     * Entity is swimming.
+     */
+    SWIMMING,
+    /**
+     * Entity is riptiding with a trident.
+     */
+    SPIN_ATTACK,
+    /**
+     * Entity is sneaking.
+     */
+    SNEAKING,
+    /**
+     * Entity is dead.
+     */
+    DYING;
+}