create.dir argument for ggsave()

[teunbrand]

This PR aims to fix #5489.

Briefly, it adds a create.dir argument to ggsave(), which controls whether a new directory can be created.
As an implementation detail, I've isolated all the path checking into its own function.

Example:

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

p <- ggplot()

ggsave("foobar/test.png", plot = p)
#> Error in `ggsave()`:
#> ! Cannot find directory 'foobar'.
#> ℹ Please supply an existing directory or use `create.dir = TRUE`.

ggsave("foobar/test.png", plot = p, create.dir = TRUE)
#> ✔ Created directory: 'foobar'.
#> Saving 7 x 5 in image

^{Created on 2023-10-24 with reprex v2.0.2}

Because the default create.dir = FALSE might be pain for interactive use, it prompts a small menu choice in interactive mode (which I don't know how to reprex)

ggsave("foobar/test.png", plot = p)
#> Cannot find directory foobar.
#> ℹ Would you like to create a new directory?
#>
#> 1: Yes
#> 2: No
#>
#> Selection: 1
#> ✔ Created directory: foobar.
#> Saving 7 x 7 in image

[olivroy]

I think that it would be better to pass down the error call to the type checks as well!

[teunbrand]

Thanks for these suggestions olivroy!

[thomasp85]

LGTM - maybe add a check for whether create.dir is NA

[teunbrand]

There is a check_bool(create.dir, call = call) in there that disallows NA values for create.dir.