Improve multi-format link options

[coatless]

Description

Consider:

my-doc.qmd

---
title: "Example"
format: 
  html: default
  ipynb: default

format-links:
  - format: ipynb
    text: Jupyter Notebook
    icon: file-code
---

Some text ...

_quarto.yml:

  render: 
    - "*.qmd"
    - "!*.ipynb"

As a result, we get both a html and ipynb output. When using Quarto links on a website, we're usually using:

[Page to link to](my-doc.qmd)

However, in the case of multi-formats, we need to remove the .qmd extension and go directly to the output file, e.g.

- [HTML](my-doc.html)
- [Jupyter Notebook](my-doc.ipynb)

The idea here would be to use an extension on the link to indicate the format that should be used from the .qmd file itself, e.g.

- [HTML](my-doc.qmd*html)
- [Jupyter Notebook](my-doc.qmd*ipynb)

Here, I'm proposing the link modification of .qmd*<format> to yield the appropriate output file resolution.