suit/transport/coap: use nanocoap for request
suit/transport/coap: use nanocoap for request

This changes the retransmission timeout behavior.
In SUIT the timeout was uses as the maximum time *all* retransmissions
could take, whereas in nanocoap the timeout was specified per retransmission.

This means that SUIT now adopts the timeout behavior of nanocoap.

miri64/RIOT,kaspar030/RIOT,OlegHahm/RIOT,jasonatran/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,ant9000/RIOT,OlegHahm/RIOT,miri64/RIOT,miri64/RIOT,ant9000/RIOT,miri64/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,kYc0o/RIOT,ant9000/RIOT,kYc0o/RIOT,miri64/RIOT,jasonatran/RIOT,jasonatran/RIOT,kYc0o/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,kaspar030/RIOT,kaspar030/RIOT,ant9000/RIOT,ant9000/RIOT,OlegHahm/RIOT,kaspar030/RIOT,OlegHahm/RIOT