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.
Linux allows the use of non-`user.` extended attributes on symlinks. One
of the main users of this functionality is SELinux's `security.selinux`
xattr for storing a path's label. By storing symlink xattrs, restic is
now suitable for backing up the root filesystem on Linux distributions
that use SELinux.
This commit adds support for symlink xattrs when backing up data,
restoring data, and mounting snapshots via a fuse mount. All calls to
the xattr library have been updated to the use `L` variants of the
various functions, which always operate on the path given, without
following symlinks.
Fixes: #4375
Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>
Also make the errors a bit less verbose by not prepending the operation,
since pkg/xattr already does that. Old errors looked like
Listxattr: xattr.list /myfiles/.zfs/snapshot: invalid argument
