Color design direction

[alice-i-cecile]

Affected PRs, issues, and discussions:

• LinSrgba, Srgba and Hsla color types #1870
• Remove ambiguous Color math implementations #3925
• [Merged by Bors] - Add conversions from Color to u32 #4088
• Add a Color lerp() method #1402
• Color operations are undefined #1849
• https://discord.com/channels/691052431525675048/743663924229963868/948912455382360114

Decisions to be made here:

• Do we need an RFC for this?
• What are the goals for Color as a type?
• Should we split the monolithic Color into multiple colorspace types?
• Should we use an external library for this? If so which one?
• What does the developer UX with the type(s) look like?

[alice-i-cecile]

@james7132, I think this was your creation originally?