bug: c stack usage in form body request

[JosiahParry]

The below request causes Error: C stack usage 16917613 is too close to the limit.
The issue is that the features parameter is a json string that is 16mb.

library(httr2)

feats <- brio::read_file("features.json")
format(object.size(feats), "Mb")

req <- request("https://httpbin.org/post") |> 
  req_body_form(
    features = feats,
    f = "json"
  )

The traceback is:

1. format.default(x, scientific = FALSE, trim = TRUE, justify = "none")
2. format(x, scientific = FALSE, trim = TRUE, justify = "none")
3. (function (x, name, multi = FALSE, form = FALSE, error_call = caller_env()) 
   {
       check_query_param(x, name, multi = multi, error_call = error_call)
       if (inherits(x, "AsIs")) {
           unclass(x)
       }
       else if (is_obfuscated(x)) {
           x
       }
       else {
           x <- format(x, scientific = FALSE, trim = TRUE, justify = "none")
           x <- curl::curl_escape(x)
           if (form) {
               x <- gsub("%20", "+", x, fixed = TRUE)
           }
           x
       }
   })(dots[[1L]][[1L]], dots[[2L]][[1L]], form = FALSE, error_call = <environment>)
4. mapply(.f, .x, .y, MoreArgs = list(...), SIMPLIFY = FALSE)
5. map2(.x, names(.x), .f, ...)
6. imap(dots[n == 1], format_query_param, form = form, error_call = error_call)
7. multi_dots(..., .multi = .multi)
8. req_body_form(request("https://httpbin.org/post"), features = feats, 
       f = "json")

The json file can be found here: features.json

Background:

A customer using arcgislayers reported this issue. They are publishing very detailed geographies. in this case, just one of the geometries in question has 430k vertices. I will see if there are alternative ways that our services can accept new geometries outside of json.