[Feature Request]: Add partial match F1 score to NER

[rajasbansal]

Is your feature request related to a problem? Please describe. Currently NER uses the library nervaluate based on the SemEval framework of evaluation. More details on this evaluation here - https://www.davidsbatista.net/blog/2018/05/09/Named_Entity_Evaluation/. We currently just support strict matching of the ground truth surface string and predicted entity surface string. Add support for partial matches to be considered while calculating accuracy.

Describe the solution you'd like Add partial matches f1 from the nervaluate evaluator output.

Additional context