It’s no secret Jeff Bezos has been looking to crack health care. But no one expected him to pull in Warren Buffett and Jamie Dimon, too.  News Tuesday that Bezos’s Amazon.com Inc., Buffett’s Berkshire Hathaway Inc. andJPMorgan Chase & Co., led by Dimon, plan to join forces to change how health care is provided to their combined 1 million U.S. employees sent shock waves through the health-care industry.