Anyone who doubts that star power is driving Broadway these days need only check the current box-office figures. A Raisin in the Sun, a revival of Lorraine Hansberry’s 1959 classic, is a sellout — thanks largely to its movie-star leading man, Denzel Washington. Of Mice and Men, John Steinbeck’s Depression-era warhorse, is another hot seller, helped by a starry cast headed by James Franco and Leighton Meester, formerly of the hit primetime soap Gossip Girl.