Define `before_starting_container` and `after_stopping_container`
functions, these functions run before and after the container that
builds the rootfs respectively.
Signed-off-by: Julio Montes <julio.montes@intel.com>
move all osbuilder files into `tools` directory to be able
to merge this into kata-containers repo.
Signed-off-by: Salvador Fuentes <salvador.fuentes@intel.com>