By Ronald Blum NEW YORK - Baseball is about to get its official boxscore on the Steroids Era. It's the Mitchell Report, the findings of former Senate Majority Leader George Mitchell's 20-month investigation into performance-enhancing drug use that has tarnished some of the game's greatest stars and records. It's due out this week, possibly Thursday, and while critics are sure to claim it's one-sided and outdated, it has given players and executives cause for pause and led some to fear a modern-day Black Sox scandal.