wic: Fix permissions when using exclude or include path

When parameters include_path or exclude_path are passed to the rootfs
plugin, it will copy the partition content into a folder and make all
the modifications there.

This is done using copyhardlinktree(), which does not take into
consideration the content of the pseudo folder, which contains the
information about the right permissions and ownership of the folders.

This results in a rootfs owned by the user that is running the wic
command (usually UID 1000), which makes some rootfs unbootable.

To fix this we copy the content of the pseudo folders to the new folder
and modify the pseudo database using the "pseudo -B" command.

Signed-off-by: Ricardo Ribalda Delgado <ricardo@ribalda.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>