### Bug description

Currently, it does not appear like we can run arbitrary R expressions by prefacing the parameter value with !r. Here is an example arbitrary of R expression parameters from the R4DS book (https://r4ds.had.co.nz/r-markdown.html#parameters). 
```
---
title: "testing"
format: html
editor: visual
params:
  start: !r lubridate::ymd('2015-01-01')
  snapshot: !r lubridate::ymd_hms('2015-01-01 12:30:00')
  name: "John"
---
```
Running on macOS Monterey Version 12.5

### `quarto check` Output

[✓] Checking Quarto installation......OK
      Version: 1.0.36
      Path: /Applications/quarto/bin

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

[✓] Checking Python 3 installation....OK
      Version: 3.8.9
      Path: /Applications/Xcode.app/Contents/Developer/usr/bin/python3
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with python3 -m pip install jupyter

[✓] Checking R installation...........OK
      Version: 4.2.1
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Users/samparmar/Library/R/4.0/library
        - /Library/Frameworks/R.framework/Versions/4.2/Resources/library
      rmarkdown: 2.8

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

### `quarto tools check` Output

_No response_

### Checklist

- [X] [formatted your issue](https://yihui.org/issue/#please-format-your-issue-correctly) so it is easier for us to read?
- [ ] included a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
- [X] documented the quarto version you're running, by pasting the output from running `quarto check` in the "Quarto Check Output" text area?
- [X] documented the version of the quarto tools you're running, by providing the output from running `quarto tools check` in the "Quarto Tools Check Output" text area?
- [ ] documented the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] documented which operating system you're running? If on Linux, please provide the specific distribution as well.
- [X] upgraded to the latest version, including your versions of R, the RStudio IDE, and relevant R packages?
2022-08-01T16:54:51Z
parmsam
bug
closed
Error using arbitrary R expressions in YAML params
https://github.com/quarto-dev/quarto-cli/issues/1629