Use multiple languages in one code block

[LONGACAT]

Support for multiple languages in one code block would be nice to have

Example mockup of what I mean:

Here lines 1-2, 6-8 use no language, 3-5 use rs and 9-13 use c. Something similar to the annotations option could work? E.g.

#codly(languages-in-block: (
  (
    start: 2,
    end: 4,
    language: "rs",
  ),
  (
    start: 8,
    end: 12,
    language: "c",
  ),
))
```
You can view a file with:
$ cat main.rs
pub fn main() {
    println!("Hello, world!");
}

Here's another one:
$ cat main.c
#include <stdio.h>
int main() {
   printf("Hello, world!");
   return 0;
}
```

Not sure how would it work with language boxes, I made a mockup for that as well:

It could either be automatic when languages get switched or manual (or selectable) with something like the following:

#codly(language-boxes: (
  (
    at: 2,
    language: "rs",
  ),
  (
    at: 8,
    language: "c",
  ),
))

[Dherse]

This may not be part of v1.2.0 but I am still thinking on how best to make this feature