Introduce a `colors` script in our cli

[mimarz]

With our new token structure we have the feature of auto-generating color scales for accent color.

We want to add the logic for generating the color scales in the cli so we can re-use it several places such as figma plugins, websites or just as pure cli script.

The color function should have names props for each color definition. When exposed through the cli, the color set could be a comma separated string.

For example npx @digdir/designsystemet add-theme Altinn --colors "#0062BA, #1E2B3C, ##F45F63, #E5AA20, #1E98F5"