Sensitive and emotional performances are the hallmark of Alisa Weilerstein, the 32-year-old cellist whom San Francisco Performances presents this weekend at St. Mark’s Lutheran Church in San Francisco. The recipient of an Avery Fisher Career Grant in 2001 and the coveted MacArthur Fellowship in 2011, she has become a champion of contemporary music — as comfortable interpreting contemporary works by Osvaldo Golijov as she is playing Bach.