Add support for Opinion Lexicon by Bing Liu and collaborators

[kou]

https://www.cs.uic.edu/~liub/FBS/sentiment-analysis.html#lexicon

tidytext calls this "bing": https://www.tidytextmining.com/sentiment.html#the-sentiments-dataset

It seems that there are some datasets: https://www.cs.uic.edu/~liub/FBS/sentiment-analysis.html#datasets I don't look at them but they will be useful.