Zoë Kravitz isn’t moping around after splitting from former fiancé Channing Tatum! Just a few days after it was revealed that the stars broke up, the actress was seen living it up with pals at a Halloween party in New York City. According to an eyewitness who was also in attendance at the exclusive bash — which took place at Chez Margaux — the Big Little Lies alum, 35, was “dancing all night and having cocktails.” “She was in a good mood and seemed really happy,” the source added of Kravitz, who was seen chatting with Glee’s Dianna Agron at the shindig. The Los Angeles native stayed until the …