Kate Aurthur editorJulia Louis-Dreyfus has created iconic characters on “Seinfeld” and “Veep,” and with her overall deal with Apple, she’s poised for her next chapter. That future may or may not include more appearances as the Marvel villain Contessa Valentina Allegra de Fontaine on Disney Plus’ “The Falcon and the Winter Soldier” — something she can barely talk about, since Marvel is so secretive.