Citing traffic concerns, Massachusetts Attorney General Maura Healey is calling upon state environmental officials to deny Wynn Resorts a key permit for its $1.7 billion casino project at the Everett waterfront. Healey said in a letter Friday to the state’s environmental affairs secretary that Wynn should not get the permit until a plan is in place to address traffic around Boston’s notoriously congested Sullivan Square area located not far from the waterfront site.