deprecate downloadData()?

[achubaty]

This is no longer the recommended approach, as it will not / cannot be guaranteed to download all data needed/used by the module (the user is likely using prepInputs, drive_download or others directly).

There are several recent failures in R CMD check using the box branch affecting this function.

─  checking examples ... [11s/11s] ERROR (10.9s)
   Running examples in ‘SpaDES.core-Ex.R’ failed
   The error most likely occurred in:
   
   > base::assign(".ptime", proc.time(), pos = "CheckExEnv")
   > ### Name: downloadData
   > ### Title: Download module data
   > ### Aliases: downloadData downloadData,character,character,logical-method
   > ###   downloadData,character,missing,missing-method
   > ###   downloadData,character,missing,logical-method
   > ###   downloadData,character,character,missing-method
   > 
   > ### ** Examples
   > 
   > ## No test: 
   > # In metadata, each expectsInput has a sourceURL; downloadData will look for
   > # that and download if it defined; however this sample module has all
   > # NAs for sourceURL, so nothing to download
   > modulePath <- getSampleModules(tempdir())
   > downloadData("caribouMovement", path = modulePath)
   Error: invalid version specification ‘cache/Require/box’
   Execution halted