Misc Polish (#1569)

* Introduced a lock for DB work during the scan to hopefully reduce the concurrency issues

* Don't allow multiple theme scans to occur

* Fixed bulk actions not having all actions due to nested actionable menu changes

* Refactored the Scan loop to be synchronous to avoid any issues. After first loop, no real performance issues.

* Updated the LibraryWatcher when under many internal buffer full issues, to suspend watching for a full hour, to allow whatever downloading to complete.

* Removed Semaphore as it's not needed anymore

* Updated the output for logger to explicitly say from Kavita (if you're pushing to Seq)

* Fixed a broken test

* Fixed ReleaseYear not populating due to a change from a contributor around how to populate ReleaseYear.

* Ensure when scan folder runs, that we don't double enqueue the same tasks.

* Fixed user settings not loading the correct tab

* Changed the Release Year -> Release

* Added more refresh hooks in reader to hopefully ensure faster refreshes

* Reset images between chapter loads to help flush image faster. Don't show broken image icon when an image is still loading.

* Fixed the prefetcher not properly loading the correct images and hence, allowing a bit of lag between chapter loads.

* Code smells

API/Services/TaskScheduler.cs

@@ -158,7 +158,13 @@ public class TaskScheduler : ITaskScheduler
 
     public void ScanSiteThemes()
     {
-        _logger.LogInformation("Starting Site Theme scan");
+        if (HasAlreadyEnqueuedTask("ThemeService", "Scan", Array.Empty<object>(), ScanQueue))
+        {
+            _logger.LogInformation("A Theme Scan is already running");
+            return;
+        }
+
+        _logger.LogInformation("Enqueueing Site Theme scan");
         BackgroundJob.Enqueue(() => _themeService.Scan());
     }