GET_FILE_UPLOAD_URL - get an upload URL for an artifact file that will be
published to NDI Cloud
Same functionality as ndi.cloud.api.datasets.GET_FILE_UPLOAD_URL
[RESPONSE,UPLOAD_URL] = ndi.cloud.api.files.GET_FILE_UPLOAD_URL(DATASET_ID, UID)
Inputs:
DATASET_ID - a string representing the dataset id
UID - a string representing the unique identifier that can be used to
reference the file in document
Outputs:
RESPONSE - the upload summary
UPLOAD_URL - the upload URL to put the file to