PROVINCETOWN — Visitors to MacMillan Pier this summer are guaranteed a sighting of a great white shark — 12 feet long and with plenty of teeth. But the toothed creature isn’t here for the seals. Rather, it is serving as a welcome for the new outpost of the Atlantic White Shark Conservancy (AWSC), which is set to open on the pier this summer in the space that for two decades housed the Whydah Pirate Museum.