Originally reported in wp-cli/extension-command#123 with a proof of concept at wp-cli/extension-command#472

As per wp-cli/extension-command#472 (comment), I think it makes sense to include validation of potentially corrupt ZIP files directly in WpHttpCacheManager.

WpHttpCacheManager could automatically do some validation based on the detected content type. So if a downloaded ZIP is corrupt, we wouldn't add it to FileCache but throw an error instead.