rasterRead() no longer returns a function

[achubaty]

rasterRead() used to return the function corresponding to the string set in reproducible.rasterRead.

this was used in e.g., overlayLCCs():

https://github.com/PredictiveEcology/LandR/blob/development/R/overlayLCCs.R#L70-L71

but this now fails because rasterRead() was modified to evaluate the function, and it now accepts and passes ... to the function, returning a SpatRaster or Raster object.

this change broke overlayLCCs() but at this point, reverting the change will likely break something else.

I will use the original version internally within this function, and note that if similar problems arise elsewhere in the package, that we may need the original version restored for general use in the package.