Implement collect_list in window context

[talegari]

From this posit community post: https://forum.posit.co/t/unexpected-sql-with-mutate-in-sparklyr/189492/2

suppressPackageStartupMessages(library(dplyr))
suppressPackageStartupMessages(library(lubridate))

rep_df <-tibble::tibble(
    user_id = sample(1:100, 1000, replace = TRUE),
    dates   = seq(as_date("2024-01-01"), as_date("2024-02-01"), 1) %>% 
      sample(1000, replace = TRUE),
    amount  = sample(seq(100, 900, 100), 1000, replace = TRUE)
  ) %>% 
  summarise(amount = sum(amount), .by = c(user_id, dates))

dbplyr::lazy_frame(rep_df) |> 
  group_by(user_id) %>%
  dbplyr::window_order(dates) %>%
  dbplyr::window_frame(-Inf, -1) %>%
  mutate(list_amount = mean(amount)) %>% 
  dbplyr::sql_render()

#> Warning: Missing values are always removed in SQL aggregation functions.
#> Use `na.rm = TRUE` to silence this warning
#> This warning is displayed once every 8 hours.
#> <SQL> SELECT
#>   `df`.*,
#>   AVG(`amount`) OVER (PARTITION BY `user_id` ORDER BY `dates` ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING) AS `list_amount`
#> FROM `df`

dbplyr::lazy_frame(rep_df) |> 
  group_by(user_id) %>%
  dbplyr::window_order(dates) %>%
  dbplyr::window_frame(-Inf, -1) %>%
  mutate(list_amount = my_func(amount)) %>% 
  dbplyr::sql_render()

#> <SQL> SELECT `df`.*, my_func(`amount`) AS `list_amount`
#> FROM `df`