feat: support `nuxt-site-config`

[dargmuesli]

Describe the feature

As discussed on Discord with @BobbieGoede and @harlan-zw, there is Harlan's amazing site-config project which aims to provide a central method for general site configuration so not every other module has to implement this itself.

nuxt-i18n allows to specify a baseUrl, which is exactly such a reimplementation. I propose to support reading the i18n.baseUrl from site.url when it is available, keeping the fallback to i18n.baseUrl.

Of course i18n.baseUrl could be marked as deprecated until the final v8 release if everything works fine outsourcing the baseUrl to nuxt-site-config to keep a separation of concerns.

Additional information

• [x] Would you be willing to help implement this feature?
• [ ] Could this feature be implemented as a module?

Final checks

• [X] Read the contribution guide (The contribution guideline of nuxt-modules/i18n is compliant with Nuxt too).
• [X] Check existing discussions and issues.

[kazupon]

That sounds good! :+1: nuxt i18n is a community based open-source project as well as Nuxt.

Let's discuss more if we need to work out any details about the specifications! of course, PR is welcome! :) /cc @BobbieGoede