Tokens: Sizing

[daneah]

The problem

Some components need to have an explicit height or width defined, and it may be beneficial for those values to be tokenized instead of hard coded.

The solution

Creating a new set of "sizing" tokens that can be used to size components. An analysis should be included as part of this that determines which things should be included (or not), and what values to settle out to (we don't want a token for every possible size).

Additional information

Some folks have been inclined to use the existing spacing tokens to represent a size, but these are really separate purposes—one is about how much room a thing takes up, while the other is how much space to place between things.