[ALOY-1233] Alloy: there’s no way to use ItemTemplates outside of ListViews

Currently ItemTemplate elements work only inside a Templates element inside a ListView. It would be great to being able to use them standalone, given that there are ore than one library out there which requires ItemTemplates-like format. See: - https://github.com/FokkeZB/css-layout-ti - https://github.com/smclab/power-templates - https://github.com/appersonlabs/Carbon