The business consultant McKinsey & Company agreed to pay nearly $600 million for its role in consulting businesses on how to sell more prescription opioid painkillers amid a nationwide overdose crisis.“We deeply regret that we did not adequately acknowledge the tragic consequences of the epidemic unfolding in our communities,” McKinsey Global Managing Partner Kevin Sneader said in a statement Thursday, noting the company cooperated with investigations. “With this agreement, we hope to be part of the solution to the …