[WIP] Check support for govuk-frontend v5

[gregtyler]

Testing with the changes to govuk-frontend in version 5 of the Design System, alongside related changes in MOJ Pattern Library.

NB: to test locally, you must copy the contents of the MOJPL package folder from its WIP branch into a folder in the root of this repo called ./moj-frontend.

Changes we have to make:

• Update path of dist files in govuk-frontend
• Remove data-module="govuk-details" (it no longer does anything)
• Use [disabled] attribute rather than govuk-button--disabled class (which has been removed)
• Update body class initialisation

I haven't added type="module" to the <script> tag because we don't need to, but we might like to do so for closer alignment with GDS guidance.

#major

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

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