Spacing presets

[neatlittlemacapps]

This magnificent article talks about spacing tokens.

Predefined sets of top/bottom/left/right spacings.
Currently you can only obtain this by right clicking a spacing. This makes it not possible to "predefined" a token with a specific spacing combi.
For instance, a "Medium" "Squished Inset" (meaning 16 px left/right and 8px top/bottom).

It would be cool to be able to create predefined spacing tokens for these combi's.

[six7]

Definitely, this would be very useful.

This also relates with #110 where we'd have multiple border radii that could be used in combination like this inset idea.