New API for Link component

[vNakamura]

The current component uses a type prop to define both the color and the behavior (hover color, underline) of the link.

This is quite confusing and constrains customization. So we should think of a new api that would allow behavior and color to be set independently.

[vNakamura]

My proposition:

Split into multiple props:

• color
• hoverColor
• decoration
• hoverDecoration

Then, instead of linkTypes constants we have presets, like:

linkPresets = {
  FEATURED: {
    color: colors.INDIGO_MILK_CAP,
    hoverColor: 'inherit',
    decoration: 'none',
    hoverDecoration: 'underline'
  },
  . . .
}

So, we use it like:

<Link href="#" {...linkPresets.FEATURED}>
  Hello
</Link>