On FreeBSD, limited users may not be able to even list xattrs for the
parent directories above the snapshot source paths. As this can cause
the backup to fail, just ignore those errors.
Add new generic_attributes attribute in Node.
Use the generic attributes to add support for creation time and file attributes like hidden, readonly, encrypted in windows. Handle permission errors for readonly files in windows.
Handle backup and restore of encrypted attributes using windows system calls.
