The musician known as “The Boss” will command two minutes of commercial time in Super Bowl LV Sunday night, all part of a mammoth Jeep ad meant to reflect a national mood of coming together after four years of politics and polarization. The spot does something else, too: It ends a decade-long quest by one of the industry’s most colorful marketing executives to convince the iconic artist behind stirring songs like “Born in the U.S.A.,” “Growing Up” and “The Rising” to do something he has never done before — align himself with an advertiser.