A predator raped a woman inside a waterfront Brooklyn park earlier this week, cops said Friday.  The sex fiend cornered the 59-year-old woman as she walked inside Kaiser Park, near the corner of Bayview and Neptune Avenues, in Coney Island around 8:20 a.m. Tuesday and sexually assaulted her, authorities said.  The NYPD released a sketch of the still-at-large perv, who police say did not know the victim.  The woman refused medical attention at the scene, police said. Surveillance footage shows