GEE support should be removed

[khufkens]

GEE is still free for academic/research use but restrictions will no doubt apply in the future.

I would like to see this removed, falling back to native R code (i.e. MODISTools) and relying on external workflows if other data is needed. STAC catalogues of the GEE data were published so subsetting using terra and R STAC implementations should be possible (but not a priority).