NOISSUE refactor pack import (extraction and paths)

It now:
* Doesn't extract until it knows the content format is good.
* Extracts in a predictable location, not requiring to use a second path for the actual pack root.

api/logic/minecraft/World.cpp

@@ -146,7 +146,7 @@ void World::readFromZip(const QFileInfo &file)
 	{
 		return;
 	}
-	auto location = MMCZip::findFileInZip(&zip, "level.dat");
+	auto location = MMCZip::findFolderOfFileInZip(&zip, "level.dat");
 	is_valid = !location.isEmpty();
 	if (!is_valid)
 	{