Improve post entry views, add post link data

CHDataManagement/Storage/PostFile.swift

@@ -35,6 +35,12 @@ struct LocalizedPostFile {
     let content: String
 
     let lastModifiedDate: Date?
+
+    let linkPreviewImage: String?
+
+    let linkPreviewTitle: String?
+
+    let linkPreviewDescription: String?
 }
 
 extension LocalizedPostFile: Codable {