Automatically add labels in the Data Labeling bulk labeling script

[Seth-Miller-Oracle]

I was trying to bulk label a dataset with 50 different labels but the script was erring out because it assumes that the labels are already added to the dataset. Rather than adding the labels one by one in the UI, I added code to the bulk labeling script to do it automatically and would like to contribute this back to the repo through a PR.

data_labeling_examples/bulk_labeling_python