ONLY 18 months ago the French-Canadian Province of Quebec reëlected the provincial Premier, Maurice Duplessis, by a huge majority he won 82 of 92 seats in the Legislature. It was a triumph of the extreme Right. Mr. Duplessis is said to have promised, and later did introduce, a labor law that made the Taft-Hartley Act look radical. He is an isolationist not only in world affairs but within Canada a violent champion of "provincial rights" who often seems to regard Ottawa as a foreign if not a hostile capital.