Boston’s business leaders are breaking out their checkbooks for a ballot question that could allow dozens of additional charter schools to open in the state. Most of the $11.5 million raised this year for the referendum — which would, if it passes in November, allow up to 12 new charter schools or expansions a year — came from out-of-state sources. But a number of prominent local leaders played a big role, according to newly released records from the state Office of Campaign & Political Finance.