There’s a current boom of family-friendly film fare inspired by beloved British literary characters, which makes this moment ripe for the animated “Sherlock Gnomes,” the sequel to 2011’s “Gnomeo and Juliet.” In terms of ranking these adaptations, “Sherlock Gnomes” is more pleasant than “Peter Rabbit,” but doesn’t touch the wonder of “Paddington 2.” It’s a serviceable animated feature, with a few inspired elements, and more than enough gnome puns to go around. The beloved British literary characters are, of course, Sherlock Holmes and Watson, as well as Romeo and Juliet.