New components and better component tests

Provides better support for component testing with react-testing-library.

Note: You should also update NotGovUK packages to ^0.7.2 (with pnpm -r up '@not-govuk/*@^0.7.2')

Also:

• We now run on Node.js v18 by default.

BREAKING:

• Enzyme has been removed. You will need to migrate your tests to react-testing-library.

Potentially BREAKING changes:

• govuk-frontend updated from v3 to v4
• restify updated from v8 to v11
• webpack-cli has been updated from v4 to v5.
• webpack-dev-middleware has been updated from v5 to v6.
• Applications now listen on IPv6 by default. See: daniel-ac-martin/NotGovUK#705