Deprecate Player#boostElytra (#9899)

The Paper method was chosen for deprecation because it was more
restrictive in that it has an isGliding check.

patches/api/Add-sendOpLevel-API.patch

@@ -9,10 +9,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 --- a/src/main/java/org/bukkit/entity/Player.java
 +++ b/src/main/java/org/bukkit/entity/Player.java
 @@ -0,0 +0,0 @@ public interface Player extends HumanEntity, Conversable, OfflinePlayer, PluginM
-      */
-     @Nullable
-     Firework boostElytra(@NotNull ItemStack firework);
-+
+     }
+     // Paper end
+ 
++    // Paper start - sendOpLevel API
 +    /**
 +     * Send a packet to the player indicating its operator status level.
 +     * <p>
@@ -23,6 +23,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @throws IllegalArgumentException If the level is negative or greater than {@code 4} (i.e. not within {@code [0, 4]}).
 +     */
 +    void sendOpLevel(byte level);
-     // Paper end
- 
++    // Paper end - sendOpLevel API
++
      // Spigot start
+     public class Spigot extends Entity.Spigot {
+