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.
Windows does not have a concept of a `change time` in the sense as Unix
has it: the field `CreationTime` of the `Win32FileAttributeData` struct
is not updated when attributes or content is changed. So from now on
we're using the `LastWriteTime` as the `change time` on Windows.