Badgen.net: Add a style/theme for light and dark mode

[styfle]

The current style of the left side of each badge is dark.

I am proposing an option for a light style or theme.

This would look good for badges like Jest or TypeScript.

Also note the color of the logo matches the color of the right side.

This could be implemented with a new query string parameter style=light or style=dark or perhaps theme=light.

Relevant discussion here: https://github.com/badgen/badgen-icons/pull/12#issuecomment-495962286

[amio]

This might goes with or after v2 😉

[amio]

labelColor supported now (so we don't need to design a dark theme :D)

https://badgen.net/badge/purple/lamborghini/cyan?labelColor=purple