Respect opt_row_striping() with pdf output

[olivroy]

Recently, some support was added for styling gt tables in pdf output

A great example is #1257 (comment)

However, there are some options that are ignored with pdf table processing

• For example opt_row_striping() does nothing

Currently, this displays a table with no colors. (numbers are present though)

---
title: title
format: pdf
---

```{r}
library(gt)
my_gt_styled <- 
exibble |> 
  gt::gt() |> 
  gt::opt_row_striping(TRUE)
my_gt_styled
```

So, I currently discovered I could use a workaround for now. This table will render as expected in pdf output.

# compute manually even rows
rows_to_span <- which(seq_len(nrow(exibble)) %% 2 == 0)

my_gt_workaround <- exibble |> 
gt() |>
  gt::tab_style(
    style = gt::cell_fill("gray85"), # cell_fill() seems to have been implemented.
    locations = gt::cells_body(rows = rows_to_span)
  )

# also need to disable processing
my_gt_workaround |> tab_options(quarto.disable_processing = TRUE)

Maybe gt could build on this workaround to make opt_row_striping() work as expected in pdf output?

Also, it would be great to document the current limitations of other formats rendering.

A lot already works, but it is hard to find. It took me a while moving between LaTeX / Quarto / gt documentation. I ended up finding what I need in the issue.

So I think it would be also great to document what is currently working, what is planned, how to work around it for now.