Bermuda Triangle is a fairly new band featuring Alabama Shakes bandleader Brittany Howard and two Nashville-based singer-songwriters, Becca Mancari and Jesse Lafser. The trio made their live debut this summer, and at the time, it looked like a one-and-done kind of thing. Today, however, they decided to make things a little more permanent with a studio version of “Rosey,” a mellow,…