Rework storage structs, link preview

CHDataManagement/Model/Item/LocalizedItemId.swift

@@ -0,0 +1,33 @@
+
+struct LocalizedItemId {
+
+    let language: ContentLanguage
+
+    let itemType: ItemReference
+}
+
+extension LocalizedItemId: Equatable {
+
+    static func == (lhs: LocalizedItemId, rhs: LocalizedItemId) -> Bool {
+        lhs.language == rhs.language &&
+        lhs.itemType == rhs.itemType
+    }
+}
+
+extension LocalizedItemId: Hashable {
+
+    func hash(into hasher: inout Hasher) {
+        hasher.combine(language)
+        hasher.combine(itemType.id)
+    }
+}
+
+extension LocalizedItemId: Comparable {
+    
+    static func < (lhs: LocalizedItemId, rhs: LocalizedItemId) -> Bool {
+        guard lhs.itemType == rhs.itemType else {
+            return lhs.itemType < rhs.itemType
+        }
+        return lhs.language < rhs.language
+    }
+}