Unit Tests & New Natural Sort (#941)

* Added a lot of tests

* More tests! Added a Parser.NormalizePath to normalize all paths within Kavita.

* Fixed a bug where MarkChaptersAsUnread implementation wasn't consistent between different files and lead to extra row generation for no reason.

* Added more unit tests

* Found a better implementation for Natural Sorting. Added tests and validate it works. Next commit will swap out natural Sort for new Extension.

* Replaced NaturalSortComparer with OrderByNatural.

* Drastically simplified and sped up FindFirstEntry for finding cover images in archives

* Initial fix for a epub bug where metadata defines key as absolute path but document uses a relative path. We now have a hack to correct for the epub.

API.Tests/Extensions/FilterDtoExtensionsTests.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Collections.Generic;
+using API.DTOs.Filtering;
+using API.Entities.Enums;
+using API.Extensions;
+using Xunit;
+
+namespace API.Tests.Extensions;
+
+public class FilterDtoExtensionsTests
+{
+    [Fact]
+    public void GetSqlFilter_ShouldReturnAllFormats()
+    {
+        var filter = new FilterDto()
+        {
+            Formats = null
+        };
+
+        Assert.Equal(Enum.GetValues<MangaFormat>(), filter.GetSqlFilter());
+    }
+
+    [Fact]
+    public void GetSqlFilter_ShouldReturnAllFormats2()
+    {
+        var filter = new FilterDto()
+        {
+            Formats = new List<MangaFormat>()
+        };
+
+        Assert.Equal(Enum.GetValues<MangaFormat>(), filter.GetSqlFilter());
+    }
+
+    [Fact]
+    public void GetSqlFilter_ShouldReturnJust2()
+    {
+        var formats = new List<MangaFormat>()
+        {
+            MangaFormat.Archive, MangaFormat.Epub
+        };
+        var filter = new FilterDto()
+        {
+            Formats = formats
+        };
+
+        Assert.Equal(formats, filter.GetSqlFilter());
+    }
+}