Get scores along with Spellcheck suggestions

### Description

As we know, lucene spellcheck [suggestsimilar()](https://lucene.apache.org/core/6_0_1/suggest/org/apache/lucene/search/spell/SpellChecker.html#suggestSimilar-java.lang.String-int-) method returns just list of suggestions, it would be good to have a way to get the scores of each suggestions.

Start with the Lucene SpellChecker.suggestSimilar(String, int) entry point and its linked API documentation. Trace how suggestions and their scores are currently produced, then review existing spellcheck callers and tests to determine the public result shape and verification needed. Done means callers can obtain each suggestion together with its score without breaking the existing suggestion behavior.

Written by the indexing model from the issue text.