Sometimes, children’s movies really are just for kids, with the kind of simplistic flash and noise created for distraction rather than art or emotion. And sometimes, children’s movies are really for adults (and, of course, interested and discerning children). Kyle Balda’s enchanting “The Sheep Detectives,” a live-action (with effectively fluffy CGI sheep) comedy written by Craig Mazin and based on Leonie Swann’s 2005 novel “Three Bags Full: A Sheep Detective Story,” fits nicely into the latter category. Its premise — a group of sheep in a small British town band together to solve a crime involving their beloved shepherd — is undeniably adorable, and its messages about friendship, loyalty, courage and even death are surprisingly moving. And, if you’ve been waiting your entire life for a movie in which Sir Patrick Stewart voices an extremely dignified sheep, I’m delighted to inform you that your time has come.…