May be hard to believe, but there are three jazz festivals in the Seattle/Bellevue area this week and next. This weekend, the Couth Buzzard Jazz Festival on Greenwood is a mini survey of the history of jazz with a feature on Charles Mingus' music Sunday night. Etienne Charles and Shemekia Copland headline the Bellevue Jazz and Blues Festival next week, and the IMP fest at the UW features Bill Frisell, Reid Anderson, Bill McHenry and Cuong Vu next week. New Releases by Jay Thomas and Gary