Publish ESM and improve support for Vite

[daniel-ac-martin]

Vite seems to be less forgiving with regards to CJS modules, and won't allow named imports from them.

This means that consumers can't import in the same way that we do within this repo (which uses the raw TypeScript).

We probably need to publish ESM alongside the CJS and allow Vite to chose which it wants to use.

We should avoid publishing only ESM as that means that all consumers need to be ESM themselves.

[daniel-ac-martin]

I've previously implemented dual packages here: staylor/react-helmet-async#235

Previously there has been a suggestion that shims should be preferred over dual packages. See:

• https://nodejs.org/docs/latest-v20.x/api/packages.html#dual-package-hazard
• https://github.com/nodejs/package-examples?tab=readme-ov-file#dual-package-hazard

[daniel-ac-martin]

Most likely this would be the easiest approach: https://github.com/nodejs/package-examples?tab=readme-ov-file#approach-2-isolate-state

[daniel-ac-martin]

Note, it should be possible to work around this as follows:

import components from '@not-govuk/components';