Styling API improvements

[maximkrouk]

I can update & integrate a builder for styling if you find it interesting, so users will be able to avoid $0... stuff
Example (needs to be updated to fully support get-only reference configuration) can be found on gist
For now, I think it's the best API for styling the UI. Also, I find your layout system very attractive, just to mention ❤️

Tagging @rebeloper, because that may also be useful for his SparkUI framework 🙂

A few days ago I found something similar to my builder https://github.com/marty-suzuki/DuctTape, but there are a few things to improve btw in both of implementations.

[maximkrouk]

See https://github.com/makeupstudio/swift-declarative-configuration