ee_Initialize(...) can manage Google drive and Google
Cloud Storage resources using the R packages googledrive and
googlecloudStorageR, respectively. By default, rgee does not require
them, these are only necessary to enable rgee I/O functionality.
All user credentials are saved in the directory
~/.config/earthengine/, if a user does not specify the email
argument all user credentials will be saved in a subdirectory
called ~/.config/earthengine/ndef.