PHILADELPHIA — There’s the tried and true: the high notes in “Lucia di Lammermoor.” There’s the new: an opera about Alzheimer’s. And then there’s the Happening, during which men and woman in red shirts and shiny black boots scooped up audience members one by one, chair and all, on a kind of handcart and trundled them off to a new vantage point in a room that offered videos, live painting, dancing and the countertenor Anthony Roth Costanzo in a red costume that made him look like a giant Easter egg. Opera in Philadelphia really can claim to offer something for everyone.