Grammy winner Ashanti, best known for hits like “Foolish” and flicks like John Tucker Must Die, has been making her presence known on the New York theater scene recently. First the triple threat hit the Gershwin Theatre’s stage back in October 2008 as part of musical Wicked’s fifth anniversary celebration. Then came the news that the starlet would ease on down the road as Dorothy in the Encores! summer production of The Wiz this summer, playing at New York City Center June 12 through July 15. Now, the budding stage star is getting to know Broadway even better, dropping in on Tony-winning musical In the Heights for a little research on May 16 (the show was directed by the same helmer (Thomas Kail) and choreographer (Andy Blankenbuehler) who’ll take the reig