Kaitlin Olson, Johnny Knoxville, Niecy Nash, Tom Kenny and Don Cheadle have been added to the cast of Netflix’s forthcoming adult animated comedy, “Agent Elvis.” The line-up of guest stars includes Ed Helms, Jason Mantzoukas, Christina Hendricks, Kieran Culkin, Chris Elliot, Asif Ali, Fred Armisen, Ego Nwodim, Simon Pegg, Craig…