As season one of Boston Lyric Opera’s “AT ITS (s)CORE” series reaches a close, its upcoming episode will feature director Sarna Lapine and Grammy-winning mezzo Kelley O’ Connor. The duo will be discussing their work on BLO’s spring 2019 production of Britten’s “The Rape of Lucretia,” with topics such as Lapine’s theater-oriented approach to rehearsals, and O’Connor’s experience with not {…}