Test that documented component options match the templates

[36degrees]

What

Add tests that validate the documented options within our component YAML files (like the button YAML file) match the actual options used within the template / macro.

If the two do not match, the tests should fail.

There is as a 'work-in-progress' branch for this work which currently does this, but needs some refactoring / documentation before it can be merged.

Why

Currently we rely on human review to ensure that the documented options match reality. During a recent firebreak project, we explored whether we could do anything to catch these in our CI process.

The work found a number of inaccuracies in the documentation options:

• attributes not documented on the breadcrumbs and select components
• describedBy mistakenly documented on textarea and character count components
• footer component YAML misformed using arguments instead of params, which means the meta object is not documented correctly in the Design System
• items[].name mistakenly documented on radios – unlike checkboxes, this can only be set globally as having a set of radios with different names doesn't make any sense
• title not documented on the tabs component

This highlights the need to automate these checks, so we can make sure our documentation is correct.

[colinrotherham]

Whilst not fully related, we've started seeing failures on our Design System v5 preview:
https://github.com/alphagov/govuk-design-system/actions/runs/5956674573/job/16157972971

Design System HTML generates duplicate slugs for nested option with the same name

E.g. Macro options for Summary list rows[].actions and card.actions are shared