fix negateContext() to preserve nested contexts

Author: rcreasi

frontend/packages/@depmap/data-explorer-2/src/utils/context.ts

@@ -260,6 +260,7 @@ export function negateContext(
       dimension_type: context.dimension_type,
       expr,
       vars: context.vars,
+      ...(context.contexts ? { contexts: context.contexts } : null),
     };
   }