Summary:
Adds a UDF for the transformer model
Adds a UDF for the sentencepiece model
Adds a UDA for fitting kmeans
Adds a UDF for taking fitted kmeans centroids, and mapping to cluster ids.

Test Plan: Added tests, and also tried end2end

Reviewers: #engineering, zasgar

Reviewed By: #engineering, zasgar

Subscribers: philkuz, zasgar

Differential Revision: https://phab.corp.pixielabs.ai/D6295

GitOrigin-RevId: 81c1a0da8b5dbd7051c11caf5caafae5568e70bb