Support for integration tests, fixes

PkmnLib.Tests/Dataloader/TypeDataloaderTests.cs

@@ -10,5 +10,13 @@ public class TypeDataloaderTests
         using var file = File.Open("Data/Types.csv", FileMode.Open);
         var library = TypeDataLoader.LoadTypeLibrary(file);
         Assert.That(library, Is.Not.Null);
+        
+        var fire = library.TryGetTypeIdentifier("Fire", out var fireId);
+        Assert.That(fire, Is.True);
+        var grass = library.TryGetTypeIdentifier("Grass", out var grassId);
+        Assert.That(grass, Is.True);
+        
+        var fireEffectiveness = library.GetSingleEffectiveness(fireId, grassId);
+        Assert.That(fireEffectiveness, Is.EqualTo(2.0f));
     }
 }