feat: support generated locale type

[BobbieGoede]

While figuring out unplugin-vue-router generates and uses its types I figured a similar approach could be used here.

This PR adds the IntlifyGeneratedTypeConfig interface which is empty by default, and a GeneratedLocale type which resolves to never if IntlifyGeneratedTypeConfig['locale'] remains unset. Maybe it should be renamed to just GeneratedTypeConfig or TypeConfig 🤔

I have updated nuxt-modules/i18n#3025 to use this approach, please try it out locally to see if it works for you locally. I'm not very experienced with types like these, just trying to imitate what seems to work for other libraries, maybe there's a better approach?

For reference, the types used in router van uvr:

• https://github.com/posva/unplugin-vue-router/blob/9f462c916443006b711c1f6a9c372467779c0046/client.d.ts#L28-L34
• https://github.com/vuejs/router/blob/06008baa91f8248ac35ff5480455aae49fe6858a/packages/router/src/config.ts#L14
• https://github.com/vuejs/router/blob/06008baa91f8248ac35ff5480455aae49fe6858a/packages/router/src/typed-routes/route-map.ts#L30-L38

When this interface is augmented like below, the Locale type will resolve to "en" | "en-GB" | "ja" | "fr" | "nl" | "de" everywhere, leaving the interface empty (no augmentatio) will use the types normally and Locale resolves to string.

declare module '@intlify/core' {
  // generated based on configured locales
  interface IntlifyGeneratedTypeConfig { 
    locale: "en" | "en-GB" | "ja" | "fr" | "nl" | "de"
  }
}

[BobbieGoede]

Looks like the type tests fail, will look into this

[kazupon]

Great Job! ❤️
I always appreciate your PR!
I have tested it locally and your PR works as expected !!

I would mind you to fix two things: 🙏

• change IntlifyGeneratedTypeConfig to GeneratedTypeConfig
• export GeneratedTypeConfig also in petite-vue-i18n pkg.

when you will fix these, we can merge your PR :)

[BobbieGoede]

Great Job! ❤️ I always appreciate your PR! I have tested it locally and your PR works as expected !!

I would mind you to fix two things: 🙏

• change IntlifyGeneratedTypeConfig to GeneratedTypeConfig
• export GeneratedTypeConfig also in petite-vue-i18n pkg.

when you will fix these, we can merge your PR :)

I have implemented your suggestions 💪

Looks like the e2e tests for windows are failing, is this related to the code or flaky? (I can't rerun the action)