No contemporary singer has made a deeper investigation of the Great American Songbook than Cécile McLorin Salvant. Any chance to hear her embody and animate the standard repertoire is a joy, whether that’s on her new orchestral album, With Every Breath You Take, or at this week’s run of shows at Little Island, the scenic park and performance space on the Hudson River. There she’ll be joined by a rotating cast including vocal luminaries from the worlds of musical theater (Lillias White) and opera (Mikaela Bennett), and the superlative pianist Sullivan Fortner.