The Isabella Stewart Gardner Museum is unique, eclectic, and highly personal. Now it’s getting a culinary makeover to match. With chef Peter Crowley at the helm, the new Cafe G opens Jan. 19. Crowley has been at the museum for a decade, but until now, his efforts were curtailed by the kitchen’s limitations: a few small electric burners and one electric convection oven. With new facilities in the Renzo Piano-designed expansion, “It’s like a cloud nine situation every day,’’ he says.