ArgWriter will write a raster to disk in ARG format.
Each instance of ArgWriter is provided a data type (e.g. int or float) to
use for output files.
Write a raster in ARG format to the specified path.
The outputFilePath argument should be the full file path (including file name and extension)
to which the raster file should be written. For example, "/var/data/geotrellis/myraster.arg".
The metadataName argument is a logical name for the raster that will be included in the raster's
metadata. It does not have to match the output filename. This filename is used by the catalog
when a raster is loaded by name as opposed to filepath.