Refactor and dd ItemUtils helper methods for item type detection

Java/src/main/java/com/gildedrose/ItemUtils.java

@@ -0,0 +1,17 @@
+package com.gildedrose;
+
+class ItemUtils {
+
+    static boolean isAgedBrie(Item item) {
+        return item.name.equals("Aged Brie");
+    }
+
+    static boolean isBackstage(Item item) {
+        return item.name.equals("Backstage passes to a TAFKAL80ETC concert");
+    }
+
+    static boolean isSulfuras(Item item) {
+        return item.name.equals("Sulfuras, Hand of Ragnaros");
+    }
+
+}