lib/ukcpio: Add CPIO extraction functionality

lib/ukcpio: Add CPIO extraction functionality

Modeled after the FreeBSD libarchive:
https://github.com/freebsd/freebsd/blob/master/contrib/libarchive/libarchive/archive_read_support_format_cpio.c

The implementation is mostly complete except that it does not yet
support symlinks.

Signed-off-by: Robert Hrusecky <roberth@cs.utexas.edu>
Signed-off-by: Omar Jamil <omarj2898@gmail.com>
Signed-off-by: Sachin Beldona <sachinbeldona@utexas.edu>
Signed-off-by: Gabriel Mocanu <gabi.mocanu98@gmail.com>
Signed-off-by: Alexander Jung <a.jung@lancs.ac.uk>
Reviewed-by: Simon Kuenzer <simon.kuenzer@neclab.eu>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Pull-Request: #179