Adds some example data (Barbie's box office)

[christopherkenny]

• Adds a barbie_box_office dataset with box office data for the Barbie movie
• Documents this data in R/data.R
• Adds a data-raw folder which is ignored by R's building process for reproducibility

I think it'd be nice to have some built-in data for use in examples. Thoughts on this @MatthewBJane and @lukepilling? I could have opened an issue, but it seemed easiest to make the PR and show what I was thinking.

[lcpilling]

This is a fantastic idea. Just playing around with the data to make a really nice simple example:

barbie_box_office |> 
    mutate(daily=daily/1000000) |>
    ggplot(aes(x = day, y = daily)) +
        geom_smooth(method = 'loess', 
            color = barbie_theme_colors["dark"],
            fill = barbie_theme_colors["light"]) +
        geom_point(color = barbie_theme_colors["medium"]) +
        labs(title = "Barbie Scatter Plot",
            subtitle="Daily box office takings",
            caption="Source: www.boxofficemojo.com",
            x="Days since release",
            y="Box office takings (million USD)") +
        theme_barbie()