[OUDS] Add "Dimension" tokens, utilities and documentation

[louismaximepiton]

Warning

Don't merge before #2744.

Related issues

Closes #2605.

Description

Remaining tasks and questions

Questions:

• Should we introduce an easy way to get all utilities in px and/or in rem (I mean not only a function px-to-rem but an option like $enable-rem-utilities that make a dupe of each utility but in rem)?
• What scenario to follow inside the _utilities.scss for utilities priority?
• What to do with the spacer and $spacers variables? It's the base of many calculations inside Boosted/Bootstrap. Do we replace them with our $ouds-dimension-base and $ouds-dimension-space-fixed?
• Choose what to keep inside the table header of https://deploy-preview-2754--boosted.netlify.app/docs/utilities/spacing#notation-for-scaled-values?
• Uncomment in api.md
• Add CSS tests
• Migration add . that are missing for classes

Done list

The following was done in the PR:

• Revert [OUDS] feat: Add "Elevation" tokens, utilities and documentation - new version #2741 changes about _ouds-maps.scss and rather introduce tokens/_composite.scss. Change all the related files.
• Introduce new Sass maps that contain all the fixed and scaled values for utilities.
• Introduce new CSS variables in the _root.scss file for the scaled utilities.
• Introduce all the new utilities (fixed and scaled).
• Introduce all new design tokens in tokens/_raw.scss and in tokens/_semantic.scss
• Checked all the new provided options.
• Quite complete migration guides.
• Introduce the documentation of sizing.md and spacing.md utilities.

To be done after the PR is merged

• Change all the occurrences of ([mp]|gap)\S?-\S?\S?\S?-?n?\d in the doc.

Motivation & Context

Types of change

• New feature (non-breaking change which adds functionality)

Live previews

• https://deploy-preview-2754--boosted.netlify.app/docs/utilities/sizing
• https://deploy-preview-2754--boosted.netlify.app/docs/utilities/spacing
• https://deploy-preview-2754--boosted.netlify.app/docs/migration
• https://deploy-preview-2754--boosted.netlify.app/docs/migration-from-boosted