Adds stubs for item endpoints

src/main/kotlin/net/halfbinary/scavengerhuntapi/model/request/ItemRequest.kt

@@ -0,0 +1,6 @@
+package net.halfbinary.scavengerhuntapi.model.request
+
+data class ItemRequest(
+    val name: String,
+    val points: Int
+)

src/main/kotlin/net/halfbinary/scavengerhuntapi/model/response/ItemResponse.kt

@@ -0,0 +1,9 @@
+package net.halfbinary.scavengerhuntapi.model.response
+
+import net.halfbinary.scavengerhuntapi.model.ItemId
+
+data class ItemResponse(
+    val id: ItemId,
+    val name: String,
+    val points: Int
+)