Prevent wildcard expressions for stopwords in simple expressions

[reebalazs]

• add stopwords to registry
• support function for getting the stopwords
• cache to optimize the parsing of stopwords.txt

This transforms the (term AND term*) expression for stopwords, removing the wildcard expression. Such an expression would never match any documents, because solr won't remove the wildcard term, but the stopword will be missing from the index. This workaround does that with no side effects, as stopwords would be ignored by solr anyway.

[tisto]

@reebalazs released with c.solr. 9.2.0.