Missing file entity filesize property

The following change will fetch the asset meta data and use the bytes property from cloudinary as the filesize property.

There's also an opportunity to reduce API hits and improve performance by caching the various CloudinaryAssetHelper calls. For example, when calling CloudinaryAssetHelper::loadAssetByPublicId multiple times Drupal is hitting the Cloudinary admin API more than is needed. Could be optimized by storing the assets in memory using a map in the CloudinaryAssetHelper service instance. I didn't implement this for now because it's not required for this change, but might be worth creating a new issue for this.