Add example items for overpowered tag to testmod

src/main/resources/data/libjf/tags/items/overpowered.json

@@ -0,0 +1,5 @@
+{
+  "replace": false,
+  "values": [
+  ]
+}

src/testmod/resources/data/libjf/tags/items/overpowered.json

@@ -0,0 +1,9 @@
+{
+  "replace": false,
+  "values": [
+    "minecraft:netherite_helmet",
+    "minecraft:netherite_chestplate",
+    "minecraft:netherite_leggings",
+    "minecraft:netherite_boots"
+  ]
+}