Core API primitive types shared between GPUI and its platform backends.
This crate sits at the bottom of GPUI's dependency graph. It holds the pure
value types — geometry (Pixels, Point, Size, Bounds, …) and colors
(Rgba, Hsla, Background, …) — that both the gpui crate and the
platform implementations depend on.
Keeping these types here means a platform backend can depend on the API
primitives without depending on all of gpui. The gpui crate re-exports
everything in this crate, so gpui::Pixels and gpui_types::Pixels name
the same type and consumers do not need to know this crate exists.