The John Lennon cynic in you may despise the cloying, feel goodery of Danny Boyle’s musical “Yesterday.” The Paul McCartney optimist in you, if such a thing exists these days—a distinction the filmmakers seem fully aware of—might be won over by the dramedy’s genuinely infectious enthusiasm and its earnest, heart-on-sleeve charms. And the romantic comedy itself, Ringo-y dopey and sentimental, yet charismatic, and containing some traces of Harrison-esque soul might split the difference.