The FDNY is no longer just a boy’s club. Two women will be sworn into top positions in the department at FDNY headquarters in Brooklyn Wednesday, a historic moment for the male-dominated agency. Laura Kavanagh will be named the department’s first deputy commissioner while Elizabeth Cascio — who has served for more than three decades — is the department’s chief of staff. Both will answer directly to Fire Commissioner Daniel Nigro. “I’m very excited,” Cascio said Tuesday. “It’s not something I had seen coming.” Cascio’s retirement papers were filed when Nigro asked her to become his executive officer in 2014.