By Riley Gutiérrez McDermid It can be hard for American companies to even know if Russian oligarchs have invested in their business. Many American companies likely have no idea that Russian oligarchs have invested in their business, an expert said Friday, but they had better find out quickly if they hope to avoid any shrapnel from international sanctions. Luciano Racco, counsel and co-chair of the trade sanctions and export controls practice at law firm Foley Hoag, told TheStreet in an interview that because most ultra-wealthy Russians invest opaquely, finding out if an oligarch owns part of y…