Translatable route param slugs

[MickL]

Describe the feature

Exemplary lets imagine the route /products/[type] should generate the following routes:

- en: '/products/shoes'
- de: '/produkte/schuhe'
- fr: '/produits/chaussures'

But all localized slugs need to be mapped to a fixed value (most likely an enum), In this example this could be ProductType.Shoe.

To archive this we need three things:

1. Map localized param (slug) to enum

Locale + Slug -> Fixed value. Basically this is a reverse translation. E.g.:

- en: '/products/shoes' -> type is ProductType.Shoe,
- de: '/produkte/schuhe' -> type is ProductType.Shoe,
- fr: '/produits/chaussures' -> type is ProductType.Shoe,
- fr: '/produits/shoes' -> type is undefined (or throw error),

This is needed e.g. for making a fetch request to the API.

2. For the current route params, tell @nuxtjs/i18n about each other localized slug

This is needed for language switching. With the example above, the following needs to be generated:

const setI18nParams = useSetI18nParams();
setI18nParams({
   en: { type: 'shoes' },
   de: { type: 'schuhe' },
   fr: { type: 'chaussures' },
});

3. Generate explicit links
When wanting to place a link, we need to get the localized slug for the current locale. E.g. with the example above, if the current locale is de then the following should be generated:

<NuxtLinkLocale :to="{ name: 'products-type', params: { type: 'schuhe' } }">
   Schuhe
</NuxtLinkLocale>

Additional information

I dont have the time to get into @nuxtjs/i18n to implement this BUT I was thinking about how to solve this for some time now and I made a sandbox where I have a fully working example with the three needed functions. I dont know if this is the best possible way (if not PLEASE make suggestions!) but maybe this could be a good starting point for @nuxtjs/i18n contributors to implement this feature.

Sandbox Repo: https://github.com/MickL/nuxti18n-localized-slugs
Sandbox Stackblitz: https://stackblitz.com/~/github.com/MickL/nuxti18n-localized-slugs?file=app/pages/products/%5Btype%5D.vue