Bluetooth: Shell: Increment SID per set

Instead of always using SID=0 for advertising sets (which can be
tricky if there are multiple advertising sets using the same SID
and address), the SID will be incremented and wrap around when
reaching the max to reduce the risk of 2 or more sets having the
same SID.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>