Revert "Player: removed useless addActionBarMessage()"

This reverts commit 7d22b2a6d7.

src/pocketmine/Player.php

@@ -2279,6 +2279,15 @@ class Player extends Human implements CommandSender, ChunkLoader, ChunkListener,
 		$this->sendTitleText($subtitle, SetTitlePacket::TYPE_SET_SUBTITLE);
 	}
 
+	/**
+	 * Adds small text to the user's screen.
+	 *
+	 * @param string $message
+	 */
+	public function addActionBarMessage(string $message){
+		$this->sendTitleText($message, SetTitlePacket::TYPE_SET_ACTIONBAR_MESSAGE);
+	}
+
 	/**
 	 * Removes the title from the client's screen.
 	 */