Add prefers- media queries

[jamesnw]

• Adds a few keys to prefers-color-scheme
• Adds prefers-contrast (for Cover the features listed in the State Of XYZ surveys #1624)
• Adds prefers-reduced-data (for Cover the features listed in the State Of XYZ surveys #1624)
• Adds prefers-reduced-motion (for Cover the features listed in the State Of XYZ surveys #1624)
• Adds prefers-reduced-transparency

I included the corresponding HTTP headers, although a case could be made for a "User Preference Media Features Client Hints Headers" feature instead.

BCD is missing the http.headers.Sec-CH-Prefers-Contrast that I would otherwise use on the prefers-contrast feature, as well as http.headers.Sec-CH-Forced-Colors that I would use on #1651.

[jamesnw]

Combined with #1673