Add indicator for items with subitems

warehouse/static/css/fontawesome.css

warehouse/static/css/fontawesome.min.css

warehouse/static/webfonts/fa-brands-400.ttf

warehouse/static/webfonts/fa-brands-400.woff2

warehouse/static/webfonts/fa-regular-400.ttf

warehouse/static/webfonts/fa-regular-400.woff2

warehouse/static/webfonts/fa-solid-900.ttf

warehouse/static/webfonts/fa-solid-900.woff2

warehouse/static/webfonts/fa-v4compatibility.ttf

warehouse/static/webfonts/fa-v4compatibility.woff2

warehouse/templates/item/list.html

warehouse/templates/layout.html