Support Shorthand Border Color/Style/Width Properties

[yuschick]

Is your feature request related to a problem? Please describe.
In the border mixin, the borderColor/Style/Width props do not accept a list of values.

Describe the solution you'd like A clear and concise description of what you want to happen.

Ideally, these shorthand properties would support a list of up to 4 values, per MDN.

The style priority in the fallbacks would be as follows:

1. Side specific (blockEndColor)
2. Axis specific (blockColor)
3. Shorthand (borderColor)