Who secretly longs for the day when Robert DeNiro will show up to someone’s famously lackluster birthday party? Yeah, that’ll happen. But what if it was Joe Manuella, the “spitting image” of DeNiro? Lookalike is a wry look at professional impersonation, a uniquely postmodern convention, where the likes of “Cher,” “Ozzy Osbourne,” “Willie Nelson,” and two “Tiger Woods” might be seen cavorting on the golf course.  TW