SQLite Hangfire (#1488)

* Update to use SQLIte for Hangfire to retain information on tasks

* Updated all external links to have noopener noreferrer

* When watching folders, ensure the folders exist before creating watchers.

* Tweaked the messaging for Email Service and added link to the project.

API/Services/Tasks/Scanner/LibraryWatcher.cs

@@ -115,6 +115,7 @@ public class LibraryWatcher : ILibraryWatcher
             .SelectMany(l => l.Folders)
             .Distinct()
             .Select(Parser.Parser.NormalizePath)
+            .Where(_directoryService.Exists)
             .ToList();
         foreach (var libraryFolder in _libraryFolders)
         {