boards: native_sim: add reboot for native_sim

Add a reboot implementation for the native_sim target which restarts
the current executable keeping the command line arguments after closing
all open file descriptors.

Signed-off-by: Adrian Friedli <adrian.friedli@husqvarnagroup.com>
Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>
Co-authored-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>