Upgrade to NHS.UK frontend v10.0.0 and support SSR

[colinrotherham]

This PR upgrades to NHS.UK frontend v10.0.0 with server-side rendering (SSR) support

All client-side behaviour is now provided by the NHS.UK frontend JavaScript API

For example:

• Button preventDoubleClick and onKeyDown behaviour is now handled in button.mjs upstream
• Skip link focusTargetRef focus handling is now handled in skip-link.mjs upstream

Visually hidden text for accessibility

For accessibility reasons, it's no longer possible to pass visuallyHiddenText: false for the following:

• Contents list links heading
• Inset text prefix
• Care card urgency level
• Warning callout prefix

Conditionally revealing content

Previously, conditionally revealing content (radios, checkboxes) would only be rendered (or fully removed) when their related input was checked. It can be difficult to keep error messages and nested form field values in sync.

Conditionally revealing content is now always rendered but toggled in/out of view using the --hidden modifier.

Accessibility issues with missing aria-controls, aria-describedby or aria-expanded are now fixed.

CommonJS workarounds

Components now use NHS.UK Frontend JavaScript instead of the following workarounds:

import CharacterCountJs from '@resources/character-count';
import CheckboxJs from '@resources/checkboxes';
import HeaderJs from '@resources/header';
import TabsJs from '@resources/tabs';

Made possible since this issue was resolved:

• Component JS files are only available in ESM syntax nhsuk/nhsuk-frontend#937

New and unsupported icons

All icons have been redrawn in NHS.UK frontend v10 along with the new "User" icon

The following icons are not supported and have been removed:

• Chevron down
• Chevron left
• Chevron right
• Close
• Em dash
• Em dash (small)
• Minus
• Plus

[colinrotherham]

I'm going to move this into ready for review whilst I finish off the upgrade-to-6.0.md guide

[JoshuaBates-NHS]

Theres quite a few changes in here around certain components (e.g. header), which could do with some updates in storybook + unit tests

UpgradeTov6 is missing in Migration guides also - that will tie together the MD added into the deployed storybook

[frankieroberto]

So much good stuff in here. Thanks @colinrotherham!

[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
2.9% Duplication on New Code

See analysis details on SonarQube Cloud

[colinrotherham]

I've confirmed with @ricksmith130 that we're happy to merge this and release 6.0.0-beta.0

it looks like my approval is still valid from before
also I've just been using the updated libraries and all is good

Also discussed with @JoshuaBates-NHS on Slack

If others have reviewed and happy go ahead, I can retrospectively review further changes and we can fix forward

Thanks all