SPRINGFIELD — William “Sam” McCann continued to fund a lavish lifestyle with campaign contributions even after the former legislator and gubernatorial candidate admitted wrongdoing to federal investigators, a prosecutor said Tuesday in the opening of a corruption trial he characterized as defined by “greed, fraud and arrogance.”McCann, 54, a former Republican state senator, was questioned four times about personal spending from campaign accounts by FBI and IRS agents in summer 2018 while he …