### Bug description

Links to file attachments not supported

### Steps to reproduce

- Create a simple quarto document that creates a link to a file
```
---
title: "5815-confluence-links-to-file-attachments-not-supported"
---

[quarto-hex-png](quarto-hex.png)
[quarto-hex-svg](quarto-hex.svg)
```

### Expected behavior

The image is uploaded as an attachment to the document and linked.  The link works and opens the attached file.  Different file types are supported.

### Actual behavior

No attachment is uploaded.  It renders just text instead of a link.

#### Workaround
```
{=confluence}
<ac:link><ri:attachment ri:filename="elephant.png"/><ac:plain-text-link-body>elephant.png</ac:plain-text-link-body></ac:link>
```


### Your environment

Mac

### Quarto check output

```bash
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.2: OK
      Dart Sass version 1.55.0: OK
      Deno version 1.33.2: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 99.9.9
      Path: /Users/amanning/projects/github/quarto/quarto-cli/package/dist/bin

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.11.2
      Path: /Library/Frameworks/Python.framework/Versions/3.11/bin/python3
      Jupyter: 5.2.0
      Kernels: julia-1.7, python3

[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........OK
      Version: 4.2.1
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Library/Frameworks/R.framework/Versions/4.2/Resources/library
      knitr: 1.42
      rmarkdown: 2.20

[✓] Checking Knitr engine render......OK
```
allenmanning
2023-06-05T14:03:10Z
allenmanning
bug publishing-confluence regression
v1.4
closed
Confluence:  Links to file attachments not supported
https://github.com/quarto-dev/quarto-cli/issues/5815