tests: bluetooth: host: Add UT for bt_id_set_adv_private_addr()

Unit test project for bt_id_set_adv_private_addr().
This part of subsys/bluetooth/host/id.c unit testing.

Signed-off-by: Ahmed Moheb <ahmed.moheb@nordicsemi.no>

# Conflicts:
#	tests/bluetooth/host/id/mocks/adv.c
#	tests/bluetooth/host/id/mocks/adv.h