[v3][Feature Request] Support alternative Markdown Renderer

[Hebilicious]

Is your feature request related to a problem? Please describe

As an alterative to Remark/MDC, it would be great if nuxt content had support for Markdown-It or MDX.

It would help migrating from an existing markdown based system to nuxt content.

For example if I have a Vitepress website with some markdown content, I would like to be able to migrate it to Nuxt Content without changing my markdown files at all. For this it would be nice to have an alternative ContentRenderer, or the ability to provide a custom one that would use mardown-it and apply the same plugins as vitepress. If it's possible to make a custom one, it would be nice to add some documentation or to streamline the interface so that the community can implement them.

Describe the solution you'd like

Providing different markdown renderer content, or giving a straightforward path to implement custom ones.

For example for MDX it could look like this :

<script setup>
const slug = useRoute().params.slug
const { data: post } = await useAsyncData(`blog-${slug}`, () => {
  return queryCollection('blog').path(slug).first()
})
</script>

<template>
  <ContentRenderer syntax="mdx" :value="post" />
  <ContentRendererMDX :value="post" />
</template>

Describe alternatives you've considered

https://bsky.app/profile/farnabaz.dev/post/3lcwxftdfjk2u
It might be possible to use remark/rehype plugins to achieve a similar result.

Additional context

#2498
#1260
#2248