Forty-two years ago a little-known, 30-something actor named Steven Spielberg played a Cook County Assessor clerk in “The Blues Brothers.” He had a few lines, such as “Can I help you?” and “Here is your receipt.” His on-screen career came and went so fast you never noticed. But that filmmaking career — well, it’s hard to overstate its importance and reach. At the 94th annual Academy Awards on March 27, Spielberg, now 75, will be a contender for best director for the eighth time. It ties him with Billy Wilder for number of nominations in the category, placing him ahead of Alfred Hitchcock and John Ford, but just behind Martin Scorsese (nine nominations) and William Wyler (12 nominations). Spielberg is also the first director to receive a nod in six different decades.