Enable Token probability based Semantic Entropy (#76)

* update NLIScorer to handle logprobs

* update SemanticEntropy class to input logprobs to NLIScorer methods

* changes related to edge cases and minor refactoring

* updated unit tests

* ruff formatting

* remove changes from BlackBoxUQ

* nliscorer class returns both SE scores

* update and rerun demo notebook

* ruff format nli.py file

* updates based on reviewer's comment

* update unit tests

* updated example notebook

* ruff formating

* ruff format nli module

* renamed entropy_type variable and additional changes

* ruff formatting

Author: mohitcek