Add a completion command that dumps the contents of a shell
completion file present in the zephyr repository.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
This file was previously located in the west repository, under scripts/.
Since it now includes knowledge about specific behavior ef zephyr
extension commands, we move it here after overhauling it completely.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>