[SDK] Enable querying default color information

[aaronreed708]

Problem/Concern

Related to #1050

This issue is to figure out, design and code how to store and retrieve the default colors, as a color palette, in the SDK. These are the colors that are initially set for the background, foreground, error, warning, info, black, white, etc before the user has even created a color palette. It would be ideal if the querying were consistent with how other color values/themes will be queried in V2.

Some questions that we may need to answer:

1. How are these colors determined and how does the SDK initialize a new design system with them?
2. How can they be queried by the UI?
   • Now that we'll have named themes, should this just be a queryable theme with a default name?
3. Will these values be different in AA vs AAA?
4. Can this default theme be modified by a user? Ask @lwnoble

Proposed Solution