move make_summary_fun() to setup_params()

[teunbrand]

This PR aims to fix #4647 (comment).

Briefly, stat_summary() and stat_summary_bin() use make_summary_fun() once per panel/group respectively, whereas it should be used once per layer. This PR moves the use of that function to the setup_params() method, so that we don't encounter the message multiple times, as per #4647 (comment).

An example:

library(ggplot2)

# Old messages
p <- ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species)) +
  stat_summary_bin(geom = "errorbar")
invisible(ggplot_build(p))
#> No summary function supplied, defaulting to `mean_se()`
#> No summary function supplied, defaulting to `mean_se()`
#> No summary function supplied, defaulting to `mean_se()`

devtools::load_all("~/packages/ggplot2")
#> ℹ Loading ggplot2

# New message
p <- ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width, color = Species)) +
  stat_summary_bin(geom = "errorbar")
invisible(ggplot_build(p))
#> No summary function supplied, defaulting to `mean_se()`

^{Created on 2024-07-03 with reprex v2.1.0}

[thomasp85]

LGTM