Feature request: Document writing to logfile + surface logfile info in a user-friendly way in various editors

[mine-cetinkaya-rundel]

When working on, particularly, a large project, there is sometimes important information in the Quarto log that is easy to miss when rendering. For example, if rendering in RStudio with "Render Book", this information is printed in the Background Jobs pane, but it scrolls away quickly, and it's not trivial to find it in there, and definitely not easy to remember to do so.

It is possible to write to a logfile with

quarto render --log my-log-file.txt

In the short term, it would be good to:

1. Document this, perhaps at https://quarto.org/docs/troubleshooting?
2. Make it possible to request a log file via the project or document yaml, so one doesn't need to render with the CLI to get it.
3. If possible, make what gets captured in the log file consistent between output formats. For example, if you have a Quarto book with an image embedded but the image file is missing, this doesn't get captured in the logfile when rendering to HTML (it's instead printed in the Background Jobs pane while previewing the book) but it is captured as an ERROR if rendering to PDF.

In the longer term (1.5?), it would be nice if editors like RStudio, VSCode, etc. could parse and surface this information in a warnings or similar pane.