Get all of the information about a file, except for its contents. When a file expires, it no longer exists, and there will be no info about it, and the fileInfo field will be blank. If a transaction or smart contract deletes the file, but it has not yet expired, then the fileInfo field will be non-empty, the deleted field will be true, its size will be 0, and its contents will be empty. Note that each file has a FileID, but does not have a filename.
