[Modules] Central configuration place for baseUrl

[manniL]

Is your feature request related to a problem? Please describe.

Several modules (sitemap, i18n, axios, http, and possibly many more 🙈) are asking in some way for the app's baseUrl. Unfortunately, most of them have their own configuration option for it (e.g. publicRuntimeConfig.axios.baseUrl, sitemap.baseUrl, ...). This creates a little more boilerplate than necessary while the url itself stays the same and reduces the risk of forgetting to set a baseUrl somewhere.

Describe the solution you'd like

Ideally, the modules access some "general" place for the baseUrl, e.g. publicRuntimeConfig.baseUrl. This would reduce the boilerplate and makes configuration easier - set and forget 😋.
This could be documented at each module documentation but maybe also in the main Nuxt documentation?

To avoid breaking changes, modules could use the "general" configuration as a fallback if no specific value is set. This could also make migration easier as it is not immediately necessary but can be hinted via warning.

[Atinux]

I think we already discussed about something like this with @pi0 and it is a good idea.

I would maybe prefix it with nuxt.baseURL

[danielroe]

In Nuxt 3 this is now configurable via app.baseURL which is accessible within modules by accessing that from the nuxt options object. At runtime it is accessible via useRuntimeConfig().app.baseURL