feat!: Support various column widths for Description List

[VincentSmedinga]

Describe the pull request

What

• Adds an option to change the width of the column containing the term
• Changes the default behaviour to make the terms fit naturally
• Widens the gap between terms and columns; they were too close together
• Fixes toggling ‘inverse color’ for the ‘rich content’ example

Why

• We received a request to support a different size than the one we offered
• Letting the size of content inform layout, like we now do, is often nicer

How

• Added a termWidth prop with three options sm, md, and lg.
• If the prop is undefined, the default behaviour applies
• Replaced the gap token with column-gap (breaking change) and started using row-gap

Checklist

Before submitting your pull request, please ensure you have done the following. Check each checkmark if you have done so or if it wasn't necessary:

• Add or update unit tests
• Add or update documentation
• Add or update stories
• Add or update exports in index.* files
• Start the PR title with a Conventional Commit prefix, as explained here.

Additional notes

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