How to track lightgbm eval performance during and post training?

[Nitinsiwach]

One can specify the eval data and eval metric for lightgbm via the validationIndicatorCol and metric parameters. How can one:

1. See the iteration by iteration evaluation metric evolution like one can with non-spark-lightgbm?
2. See the evaluation evolution information (from point 1) post model training. At least something like transformer.bestEvalScore(evalDataId, evalMetricId). Best would be something like tranformer.getEvalResults(evalDataId, evalMetricId). Of course, the evalDataId and evalMetricId need to have been assigned before the training started

AB#1984493

[mhamilton723]

Tagging in the expert: @imatiach-msft