Danielle Turchiano Senior Features Editor, TVSPOILER ALERT: Do not read if you have not yet watched the series finale of “The Good Lord Bird” on Showtime.John Brown’s (Ethan Hawke) journey may have come to a violent end, but his mission will live on in the young man he inspired, Henry aka Onion (Joshua Caleb Johnson).The series finale of Showtime’s “The Good Lord Bird,” the seven-part adaptation of James McBride’s 2013 novel of the same name that looked at abolitionist John Brown’s movement