Check ellipses in several places

[teunbrand]

This PR aims to fix #3196.

Briefly, there are several places where funneling arguments through ... is now checked.
These function now perform checks:

• fortify()
• get_alt_text()
• labs()

#3196 (comment) also identified guides() and labeller() as function that should but do not perform ... checks, but these are somewhat more complicated.

Reprex from the comment:

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

# fortify now warns
p <- ggplot(mpg, aes(displ, hwy, colour = drv), foo = "bar") +
  geom_point() +
  guides(
    # legends now warn
    colour = guide_legend(non = "sense"),
    # non existing aesthetics are still silently accepted
    foobar = "qux" 
  ) +
  facet_wrap(
    ~ year,
    # labeller args are still silently accepted
    labeller = labeller(year = label_both, nonsense = label_value)
  ) + 
  labs(
    alt = "my alt text",
    # unknown labels are no longer ignored
    i_dont = "exist"
  )
#> Warning in fortify(data, ...): Arguments in `...` must be used.
#> ✖ Problematic argument:
#> • foo = "bar"
#> ℹ Did you misspell an argument name?
#> Warning in guide_legend(non = "sense"): Arguments in `...` must be used.
#> ✖ Problematic argument:
#> • non = "sense"
#> ℹ Did you misspell an argument name?

# Labels are checked during build time
p <- ggplot_build(p)
#> Warning: Ignoring unknown labels:
#> • `i_dont = "exist"`

# Extra arguments are no longer ignored
get_alt_text(p, hamspam = "green eggs")
#> Warning in get_alt_text(p, hamspam = "green eggs"): Arguments in `...` must be used.
#> ✖ Problematic argument:
#> • hamspam = "green eggs"
#> ℹ Did you misspell an argument name?
#> [1] "my alt text"

^{Created on 2024-08-06 with reprex v2.1.1}

[thomasp85]

LGTM