Casino mogul Steve Wynn, in his first public appearance in Massachusetts since winning the lucrative Boston-area gambling license, promised on Thursday that his $1.6 billion resort for the Everett waterfront will echo the “grand hotels” of the past, offering the largest hotel rooms outside of Las Vegas and other luxury amenities. “It’s the non-casino things that people get on airplanes and put up with body searches and stuff like that for,” he said at a real estate industry seminar at the Boston Convention and Exhibition Center.