[FEATURE] Support FontAwesome Icons for Markers

[rsh52]

Feature Request Description

It would be nice to also allow for fontawesome icons in addition to shapes/glyphs and emojis. the fontawesome package does not currently seem capable of doing this, but emojifont might.

Additional Context

Here is an example output using geom_text and the emojifont package:

library(ggplot2)
library(emojifont)
library(dplyr)

df <- cars |> 
  mutate(
    label = case_when(speed > 16 ~ emojifont::fontawesome("fa-car"),
                      .default = emojifont::fontawesome("fa-bicycle"))
  )

ggplot() +
  geom_text(data = df,
            aes(x = speed, y = dist, label = label, colour = label),
            family = 'fontawesome-webfont', show.legend = TRUE) +
  theme(legend.text=element_text(family='fontawesome-webfont'))

Checklist

• [ ] The issue is atomic
• [ ] The issue description is documented
• [ ] The issue title describes the problem succinctly
• [ ] Developers are assigned to the issue
• [ ] Labels are assigned to the issue

[skadauke]

A few comments here.

• I noticed that emojifont uses a very old version of FA, v0.4, and the current version is 6.6. We should use 6.6 because it'll look a lot better.
• emojifont packages the TTF font file from the fontawesome-free-web package that you can download from the FontAwesome website. It's in inst/fonts/. This appears to be OK by the SIL OFL 1.1 license which is very permissive in packaging fonts along with software, and it seems that as long as we don't modify the files and include the LICENSE.txt in the package we're good. This makes things easy and we should be able to just add the fonts we want to the ggswim package.
• I believe geom_text() supports TTF only. The following TTF fonts are in the webfonts package. I think we should support regular and solid, not brands, and there's no need to provide compatibility with v4:
  • fa-brands-400.ttf
  • fa-regular-400.ttf <- include
  • fa-solid-900.ttf <- include
  • fa-v4compatibility.ttf
• I don't think we need to support the "Pro" fonts.
• If geom_text() is cumbersome (looks bad or positioning is difficult) we could also look into using PNG or SVG versions of these fonts, also available in the package.