Combine spacing and layout tokens

[mattrosno]

Summary

We currently have two distinct spacing and layout scales. The spacing scale is defined as:

Used for smaller, more refined spacing needs, specifically within the context of a component (i.e. the space between a label and a text input).

With the layout scale:

Typically used for positioning components on a page (i.e., the space between a text field and a selector).

We have determined that there is a lot of overlap between the scales and that the tokens weren't used exactly as defined above. Because of that, the two scales lost their meaning.

Job stories

1. When designing and building an interface, I don't want to have to choose between two equal tokens, so I can easily apply the right spacing.

Success measures

1. Layout token values have been added to the spacing scale
2. Layout tokens have been deprecated
3. Website and GitHub docs have been updated

Sponsoring team

Carbon team

[mattrosno]

Issue: carbon-design-system/carbon#5602

[mattrosno]

Release: https://github.com/carbon-design-system/carbon/releases/tag/v10.32.0