fix: respect width aesthetic

[Yunuuuu]

fix #6575

n <- vapply(
    split(mpg, ~cyl),
    function(d) length(unique(d$class)),
    integer(1L)
)

dplyr::mutate(mpg,
    width = length(unique(class)),
    median = length(unique(class)) / 2L,
    .by = cyl
) |>
    ggplot() +
    geom_boxplot(
        aes(median, hwy, group = median, width = width)
    ) +
    facet_wrap(vars(cyl), nrow = 1L, space = "free_x", scales = "free_x") +
    ggh4x::facetted_pos_scales(
        lapply(n, function(max) scale_x_continuous(limits = c(0, max)))
    )

[teunbrand]

I would like to add optional_aes = "width" to the StatBoxplot class, if we're going to treat it as an aesthetic.

[teunbrand]

Lovely, thank you for adopting the proposals!
If you want, you can add a bulletpoint to the news file