LAS VEGAS — Ted Cruz has hundreds of influential Republican donors and Jewish leaders all to himself this weekend in Las Vegas as he addresses the Republican Jewish Coalition. Cruz's rivals for the GOP presidential nomination, Donald Trump and John Kasich, declined invitations to attend — a puzzling move in particular for Trump as he tries to project himself as a party unifier who deserves the Republican nomination even if he falls short of winning enough delegates in the primaries to clinch it outright....