Backwards Coppertability

- Added the option to ship opt-in resource packs

src/main/java/com/simibubi/create/Create.java

@@ -31,6 +31,7 @@ import com.simibubi.create.foundation.data.recipe.ProcessingRecipeGen;
 import com.simibubi.create.foundation.data.recipe.SequencedAssemblyRecipeGen;
 import com.simibubi.create.foundation.data.recipe.StandardRecipeGen;
 import com.simibubi.create.foundation.networking.AllPackets;
+import com.simibubi.create.foundation.utility.ShippedResourcePacks;
 import com.simibubi.create.foundation.worldgen.AllWorldFeatures;
 import com.tterrag.registrate.util.NonNullLazyValue;
 
@@ -131,6 +132,7 @@ public class Create {
 		BuiltinPotatoProjectileTypes.register();
 
 		CHUNK_UTIL.init();
+		ShippedResourcePacks.extractFiles("Copper Legacy Pack");
 
 		event.enqueueWork(() -> {
 			AllTriggers.register();

src/main/java/com/simibubi/create/foundation/utility/ShippedResourcePacks.java

@@ -0,0 +1,33 @@
+package com.simibubi.create.foundation.utility;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.FileAlreadyExistsException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+public class ShippedResourcePacks {
+
+	public static void extractFiles(String... packs) {
+		FilesHelper.createFolderIfMissing("resourcepacks");
+
+		for (String name : packs) {
+			InputStream folderInJar = ShippedResourcePacks.class.getResourceAsStream("/opt_in/" + name + ".zip");
+
+			try {
+				Files.copy(folderInJar, Paths.get("resourcepacks/" + name + ".zip"));
+			} catch (FileAlreadyExistsException e) {
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+
+			try {
+				folderInJar.close();
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		}
+
+	}
+
+}