Festival of Contemporary Music Chamber Music Sunday, July 30, 2023   LENOX – There were a number of firsts on the July 30th chamber music concert. I have never seen the stage at Ozawa Hall require several minutes of vacuuming up bits of wood, but Malin Bång’s Arching, for amplified cello, amplified tools, and electronics, created considerable, if entertaining, mayhem. Another first: hearing “The Wheels on the Bus Go Round and Round,” paired in fugal counterpoint with the Brahms lullaby.    The find for me at FCM was Tebogo Monnakgotla, a Swedish composer who curated Sunday’s concert. The aforementioned nursery