[INF] Merlin commons - Operators

[viswa-nvidia]

• Make a decision around how much we want to do in the model vs how much we want to do in operation graphs?
• Come up with a consistent way to do padding (in the dataloader) so that we can use the same function for training, dataloading and serving
• Establish how we handle data transformations for small batches in a relatively standard way
• Dictionary/dataframe translation
• Optimizing Merlin operators for serving and dataloading (small batch)
• NVTabular - Simplify and standardize Categorify(), so that unique values parquet can be used for reverse categorify