Fabric original biomes

- Capture original biomes at Fabric mod init so generated biome definitions exclude Fabric biome modifications
- Test the generated definition against a biome modified in place the way Fabric does it

adapters/fabric/src/main/java/art/arcane/iris/fabric/IrisFabricBootstrap.java

@@ -17,6 +17,7 @@ public final class IrisFabricBootstrap implements ModInitializer {
     public void onInitialize() {
         NativeFabricLoader loader = new NativeFabricLoader(new NativeLoaderOptions(
                 "irisworldgen", "treefeller", ModdedTreeFellerService::runBreakProbe));
+        loader.captureOriginalBiomes();
         NativeChunkGeneratorDefinition generator = IrisModdedChunkGenerator.DEFINITION;
         NativeFabricPackSources.bind(ModdedForcedDatapack::repositorySource);
         ModdedEngineBootstrap.bootCommon(loader, "Fabric", () -> NativeFabricBootstrap.registerGenerator(generator));