Newbury Street shoppers and others, including a few who were doing some al fresco chardonnay sipping, were surprised Friday when the graduates of Boston Architectural College — decked out in caps and gowns — took the traditional commencement stroll from Hereford Street to Old South Church. The 159 grads were joined in the procession by a jazz band, friends, faculty, and the day’s featured speaker, renowned architect-urban planner Moshe Safdie (center, alongside BAC president Glen LeRoy).