[Pitch] Unifying Package Products and Targets

Hi all, Building on recent proposals to improve the expressivity of package manifests, I'd like to share a proposal to unify SwiftPM's concept of products and targets. This is a major change to SwiftPM's build model, so I'm sharing it a little earlier than I would otherwise to collect feedback on the overall design. There is the beginning of an implementation available, but right now it's quite minimal and just enough to explore some of the design ideas in the proposal. I'm looking forward to y...