Sitemap for repo with 2 domains should offer an optional function to apply to the strings.

[disrae]

Summary

The Astro config does not have access to the slug, so the sitemap generator can only access one domain, there is no data to make the domain dynamic with.
For repos with two domains it would be nice pass a function to the generator which is applied to the url strings as they are generated.

Background & Motivation

For repos that implement two or more domains based on locale (my case), I need to be able to generate a sitemap that has the correct domain for each slug. For every slug that has '/en-us' in the string I want to switch out the domain.

Goals

A lightweight, non-breaking change to give more custom control in the sitemap generation process.

Example

I would simply want to add it in the options object for the sitemap generator.