Democrats have for more than a year gone to bat against a billionaire president and his Cabinet full of wealthy executives, railing against their conflicts of interest and accusing them of satisfying their lavish tastes on the taxpayers’ dime.But in their quest to reclaim the governorship of the nation’s third-largest blue state, Democrats in Illinois have turned to a billionaire of their own to match up against the Republican multimillionaire in office, Bruce Rauner.J.B.