Using a queryText which results in zero tokens causes a query to be built as null [LUCENE-9367]

If a queryText produces zero tokens after being processed by an Analyzer, when you try to build a Query with it the result is null.

The following code reproduces this bug:

```java
public class LuceneBug {
public Query buildQuery() throws IOException {
Analyzer analyzer = CustomAnalyzer.builder()
.withTokenizer(StandardTokenizerFactory.class)
.addTokenFilter(StopFilterFactory.class)
.build();

QueryBuilder queryBuilder = new QueryBuilder(analyzer);

String onlyStopWords = "the and it";
return queryBuilder.createPhraseQuery("AnyField", onlyStopWords);
}
}
```

---
Migrated from [LUCENE-9367](https://issues.apache.org/jira/browse/LUCENE-9367) by Tim Brier, updated Dec 03 2020

Start with the provided LuceneBug reproduction, focusing on QueryBuilder.createPhraseQuery and the CustomAnalyzer configuration using StandardTokenizerFactory and StopFilterFactory. Trace the zero-token case and determine the intended query result before adding a regression test that captures the agreed behavior.

Written by the indexing model from the issue text.