Slight refactor to clean up resource loading from plugins

PkmnLib.Tests/Dataloader/ItemDataLoaderTests.cs

@@ -1,4 +1,5 @@
 using PkmnLib.Dynamic.Libraries.DataLoaders;
+using PkmnLib.Dynamic.ScriptHandling.Registry;
 
 namespace PkmnLib.Tests.Dataloader;
 
@@ -7,7 +8,9 @@ public class ItemDataLoaderTests
     [Test]
     public async Task TestPrimaryItemFile()
     {
-        await using var stream = File.OpenRead("Data/Items.json");
+        IResourceProvider plugin = new Plugin.Gen7.Gen7Plugin();
+        var result = plugin.GetResource(ResourceFileType.Items)!;
+        await using var stream = result.Open();
         var library = ItemDataLoader.LoadItems(stream);
         await Assert.That(library).IsNotNull();
     }