`quarto_preview` could return `serve_url`

[cwickham]

Unlike running quarto preview on the Terminal, quarto_preview() gives no information about where the preview is running.
Perhaps run_serve_daemon could:

• compute serve_url earlier

  quarto-r/R/daemon.R

  Line 132 in 60d23e4

  serve_url <- quarto[[url_key]] %||% paste0("http://localhost:", port)

• include serve_url in the message that indicates the server is running:
  

  quarto-r/R/daemon.R

  Lines 121 to 122 in 60d23e4

  	# indicate server is running
  	cat(paste0("Stop the preview with quarto_", command, "_stop()"))

• return serve_url invisibly so that quarto_preview() could also return it invisibly.

[cderv]

include serve_url in the message that indicates the server is running

I thought when quiet = FALSE, the log from Quarto would show the right thing:

> > xfun::in_dir("C:/Users/chris/Documents/DEV_OTHER/00-TESTS/test-quarto", quarto::quarto_preview("index.qmd"))


processing file: index.qmd
1/7                  
2/7 [unnamed-chunk-1]
3/7                  
4/7 [unnamed-chunk-2]
5/7                  
6/7 [unnamed-chunk-3]
7/7                  
output file: index.knit.md

pandoc 
  to: html
  output-file: index.html
  standalone: true
  section-divs: true
  html-math-method: mathjax
  wrap: none
  default-image-extension: png
  variables: {}
  
metadata
  document-css: false
  link-citations: true
  date-format: long
  lang: en
  title: Sales Report
  
Output created: index.html

Watching files for changes
Browse at http://localhost:4146/index.html

ℹ Stop the preview with `quarto::quarto_preview_stop()`

There is browsing at. Are you expecting it differently?

return serve_url invisibly so that quarto_preview() could also return it invisibly.

Good idea ! I will add this. It will be useful when quiet = TRUE