GLC FCS30

[gbenz23]

1. Relevant code is located in ..R/data_glc.R
2. GLC (v2) appears in /data_raw/sources.csv
3. URLs accessible from ../inst/extdata/urls/f37f3b1c-...
4. Change made to ´robust_transformation´ in ../R/utility.R

[krihelskog]

Thank you, Garret, for your efforts. Here are my review and comments.
One thing I wonder, which Jonas is better equipped to comment on, is the number of .zip files to download, especially given their sizes. Is it a good idea to have users download 36 .zip files in one batch? This also makes me question using beta_test and folder_size, since users must download the raw data into their folder before they can make use of get_pgfile(). So I'm not sure if beta_test and folder_size arguments are adding what you intend them to do?

Also:
Avoid loading libraries within functions (as in function 2), use terra::rast() instead.

There should not be any empty space between the end of the documentation (typically with @export) and the start of the function.