[ALOY-1702] Improve support for SFSymbols and SemanticColor in Alloy markup

Description

In 8.2.0 we introduced support for SFSymbols and Semantic Colors, these are both accessed via methods Ti.UI.iOS.systemImage and Ti.UI.fetchSemanticColor respectively. There's no great user story currently for consuming these in XML views or TSS. I think there's 2 avenues for supporting theses, either allow their direct usage or invent a shorthand (à la L()) for them. I think it's possible that we may want to restrict Ti.UI.iOS.systemImage to TSS only though, as this needs to be gated in a version check (or maybe we can get inventive and add this to the generated code ourselves?) I'll update this ticket with some proposals after some research