The last time this reviewer saw Mogwai, they were playing with Bardo Pond at the El Rey Theatre in Los Angeles in 2001. They were touring for “Rock Action” at the time, and they came across as shy, Scottish nerds, noodling with their guitars while the audience just stared in amazement. The Mogwai that played the 9:30 Club on Wednesday was the same band, plus a whole lot of keyboards. The great thing about…