LAS VEGAS — The billionaire investor Steven A. Cohen may be barred from managing outside money until next year, but he has already hinted that he plans to get back into the hedge game. The most telling sign yet? Mr. Cohen’s unexpected appearance at a Las Vegas hedge fund conference this week. Mr. Cohen was seen late on Thursday night playing craps at a table in the casino of the Bellagio Las Vegas hotel, one of Las Vegas’s most extravagant hotels. Mr. Cohen, 60, was rolling the dice with Ilana Weinstein, a sister of the hedge fund manager Boaz Weinstein,...