“The rush of time drives ‘Angels in America’ — first as Tony Kushner’s gargantuan Broadway play about AIDS, politics and morality, and now in an operatic setting by Peter Eotvos. Written for the Théâtre du Châtelet in Paris and produced for an American audience by Opera Unlimited at the Calderwood Pavilion here on Friday night, “Angels” as opera thrives on characters who — in their varying pettiness, nobility, cowardice, heart and sheer size of personality — were operatic before there was music to make them so.”