These days — let us hope, for not too much longer — a movie has to be something special to lure an audience into a theater; something you just can’t wait to see, something that would be diminished if watched on a screen at home. Unfortunately, Kenneth Branagh’s “Death on the Nile” is not one of those movies. It’s a perfectly serviceable entertainment, albeit one that’s been hit with more than its share of bad luck: multiple delays of its original December 2020 release date, due to the pandemic and to sexual assault allegations against star Armie Hammer (who’s been neatly reduced to blink-and-y…