Grammy-winning duo FOR KING & COUNTRY and chart-topping country artist Jimmie Allen will sing each other's hits during "CMT Crossroads: FOR KING + COUNTRY & Jimmie Allen" later this month. The one-hour television special will premiere on February 28 at 10p/9c, with an immediate encore at 11p/10c and additional airings on March 5 at 11a/10c…