[#3857]: Upgrade stencil

[oakenroot]

Summary of the changes

Second of a few dependency PRs, with the end goal of reducing advisories and usage of deprecated packages. This makes three commits:

1. Upgrade @stencil/core
2. Update various auto-generated files
3. Make a one-line fix that couldn't be done automatically

So while the diff is large here, there's not actually much going on/this would be easy to replicate locally

Related issue

#3857

Checklist

General

• Changes to docs package checked and committed.
• All acceptance criteria reviewed and met.

Testing

• Relevant unit tests and visual regression tests added.
• Visual testing against Figma component specification completed.
• Playground stories in React Storybook up to date, with any prop changes and additions addressed.
• Compare performance of modified components against develop using Performance addon in React Storybook.

Accessibility

• Accessibility Insights FastPass performed.
• A11y unit test added and yields no issues.
• A11y plug-in on Storybook yields no issues.
• Manual screen reader testing performed using NVDA and VoiceOver.
• Manual keyboard testing for keyboard controls and logical focus order.
• Correct roles used and ARIA attributes used correctly where required.
• Logical heading structure is maintained, and the HTML elements used for headings can be changed to fit within the wider page structure.

Resize/zoom behaviour

• Page can be zoomed to 400% with no loss of content.
• Screen magnifier used with no issues.
• Text resized to 200% with no loss of content.
• Text spacing increased as per the WCAG 1.4.12 success criterion with no loss of content.

System modes

• Browser setting 'prefers reduced motion' tested. No animations or motion visible whilst this setting is on.
• Windows High Contrast mode tested with no loss of content.
• System light and dark mode tested with no loss of content.
• Browser support tested (Chrome, Safari, Firefox and Edge).

Testing content extremes

• Min/max content examples tested with no loss of content or overflow.
• All prop combinations work without issue.
• Tested for FOUC (Flash of Unstyled Content) in both SSR (Server-Side Rendering) and SSG (Static Site Generation) settings.
• Controlled and uncontrolled input components tested.
• Props/slots can be updated after initial render.

[oakenroot]

There's one test here that failed in CI which I can't replicate locally, not sure what's going on... (in packages/react/src/component-tests/IcSideNavigation/IcSideNavigation.cy.tsx)

Would be helpful if one of the actual devs could lend a hand and give a quick look!

[GCHQ-Developer-530]

There's one test here that failed in CI which I can't replicate locally, not sure what's going on... (in packages/react/src/component-tests/IcSideNavigation/IcSideNavigation.cy.tsx)

Would be helpful if one of the actual devs could lend a hand and give a quick look!

Hi @oakenroot, we were also having this issue when trying to upgrade Stencil. They seem to be flaky tests but after quite a bit of investigation we couldn't find a way to get them to run consistently, hence us parking the ticket for a little while to work on some higher priority work within the team. Something we did consider was moving from Electron to Chrome to run the Cypress tests, but we didn't get around to implementing it.

[oakenroot]

Closing for now, will work on this on my fork where I can run tests in CI more freely. Will reopen when things are passing.