FreqFilteringScorerWrapper and min/max freq options on TermQuery [LUCENE-3395]

A Solr User was asking about how specify a minimum tf when searching for a term (ie: documents matching "dog" at least 3 times).

Based on a conversation with rmuir on IRC, that led me to realize that we now explicitly expose a general "freq()" method on Scorer, and that min/max freq constraints could be implemented as a general Scorer Wrapper.

I propose that we add such a wrapper, and add setMinFreq(float)/setMaxFreq(float) methods to TermQuery (similar to the minNumShouldMatches and disableCoord type setters in BooleanQuery) that cause it to be used automatically.

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Migrated from [LUCENE-3395](https://issues.apache.org/jira/browse/LUCENE-3395) by Chris M. Hostetter (@hossman), updated Sep 03 2018
Attachments: [LUCENE-3395.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-3395/LUCENE-3395.patch)
Linked issues:
- #9351

Start by reading the TermQuery and Scorer entry points, then inspect the attached LUCENE-3395.patch and the discussion history. Done means the proposed general frequency-filtering wrapper and TermQuery min/max frequency options are implemented consistently with the issue's requested behavior.

Written by the indexing model from the issue text.