When the Isabella Stewart Gardner Museum’s new wing opens, it will host the first US museum solo show of the work of Victoria Morton - and perhaps that’s only fitting. Morton, a Glasgow, Scotland-based painter best known for heavily textured three-dimensional images, was an artist-in-residence at the Gardner in 2009 and part of 2010. Also a guitarist, she will play with her rock band “Muscles of Joy,’’ whose six members are all women artists.