Additional color picker modes

[Keavon]

Graphite's color picker currently works with an HSV square. We should add additional modes for visualizing and parameterizing more color models.

Some of the models can include:

• HSL
• RGB
• CIE LAB (and LCH, the cylindrical form)
• OKLAB (and OKLCH, the cylindrical form)
• CIE XYZ
• CIE LUV

Some of the visualization shapes can include:

• Square
• Circle
• Triangle
• Color solid slices

Some of these, like HSL and RGB squares, can likely be implemented sooner while more complex visualizations and color spaces should likely wait until later when we can render them using Graphene instead of HTML and when our internal color data format can represent them.