Implement .get()/.getAll()/.set()/.setAll() syntax from Color API

[LeaVerou]

When @svgeesus and I defined the Color API instead of the exotic properties we use in Color.js we went with .get() and .set() methods that are more consistent with the rest of the Web Platform, since there's guidance to avoid exotic properties as they conflate object properties with data.

These methods have several advantages over the current syntax:

• Object properties clearly separate from data
• Ability to look up coordinates by ColorSpace object which allows for anonymous color spaces
• Ability to set multiple coordinates at once, or even in a relative way
• Properties hide the fact that these are actually performing conversion behind the scenes. It's easy for someone to use color.lch.lightness and then later on color.lch.chroma without ever thinking of caching color.lch. OTOH, we could cache it behind the scenes.
• Currently color.to() to convert to another Color object is a method, but color.<colorspace> to get coordinates in another colorspace is a property. This is pretty weird, and I've often done things like color.lch expecting a color and not an array.

These methods should also be implemented in Color.js, so that it can be used as a polyfill of the Color API.

[LeaVerou]

This is done after recent commits, not sure why this wasn't auto closed.