Better color API

[vgskye]

Currently the colorspace-related APIs in Color is a mess, putting Linear sRGB values in Color and all other colorspaces just using Vector4 without any safeguards against confusing, say, HSL for HSV. This PR adds the Colors namespace, which holds actually typed color classes with methods for converting between them as appropriate.

Opened as Draft because I want to add more features(mainly Oklab gamut clipping) and have colorspace parity with Color, and then add deprecations to the existing Color colorspace API while making them be wrappers over the Colors API.

[ZeWaka]

What's the purpose of including sycc?

[vgskye]

parity with existing Color API, mostly.

[vgskye]

I have now added ToColor() methods to all Colors API structs and ToXXX() methods to Color so it's much more ergonomic to use for the common case of "convert to some other colorspace, do work, convert back to sRGB". The Color methods also use the same method names as the old API, just as instance methods instead of static.

[ZeWaka]

👀