Multi-scene app using TCA

[josephktcheung]

This is a discussion that was migrated from #1282 (comment), where I was trying to find out a way to set up a multi scene app that scope both state and environment / dependency to be scene specific. This topic is not specific to protocol beta and it's better to have a separate thread of its own so that community members can share their experience of creating a multi scene app.

Best,
Joseph