Preivew button use smart knit

Is your feature request related to a problem? Please describe.
I use following yaml header in my Rmd file:

---
title: "vignette"
output: 
  bookdown::html_vignette2:
    fig_caption: true
    number_sections: true
    global_numbering: true
vignette: >
  %\VignetteIndexEntry{vignette}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
knit: (function(input, ...) {
    rmarkdown::render(
      input,
      knit_root_dir = dirname(input),
      intermediates_dir = dirname(input)
    )
  })
---

when we use a custom knit function in the yaml header like above, the knit button will work well but the preview will stop with error since I set intermediates_dir in the yaml header knit function

Describe the solution you'd like
Preview buttom do the same of smart knit button

Start by locating the VS Code Preview and Smart Knit command entry points and compare how each invokes the R Markdown knit function, especially its handling of intermediates_dir. Done means Preview follows the Smart Knit behavior for this custom YAML knit function without the reported error.