Started the Split

Split Json data models coming from REST Api, from the Database models
storing them in a SQLite database.
Work to re-engineer endpoints to use Database objects, and copy/update
data from the json objects.
More work is needed.

FreeTubeSync/Model/Json/SearchHistoryJson.cs

@@ -0,0 +1,10 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace FreeTubeSync.Model.Json;
+
+[SuppressMessage("ReSharper", "InconsistentNaming")]
+public class SearchHistoryJson
+{
+    public string _id { get; set; } = string.Empty;
+    public long lastUpdatedAt { get; set; }
+}