Even if Carl Donakowski wasn’t scheduled to perform as a cellist for the Leelanau Summer Music Festival, his thinking fingers would hint that he’s a musician. His faintly summer-tan hands curve around his coffee cup, tap the table in syncopation, and pause above the tabletop, like a conductor about to lead his orchestra into a piece. Donakowski plays chamber music, though. Chamber music has no conductors. The genre is an elegant deviant in the musical world, and it will soon be heard in Leelanau.