Iolani School, one of the largest and most-prestigious private schools in Hawaii, is expanding its Honolulu campus to include new classrooms, studios and labs for the lower school, as well as the construction of a dormitory to restore the school’s boarding program, the school said Thursday. Honolulu-based G70, formerly known as Group 70 International, is the architect for the project, which is estimated to cost between $30 million and $40 million. Timothy Cottrell, head of school for Iolani,…