Hunspell and suggester should make their temp dir configurable [LUCENE-5655]

Both the hunspell dictionary and search suggesters use `OfflineSorter`. However, the constructor they use always uses java.io.tmpdir (and will fail if the tmpdir does not already exist).

Both of these should have constructors that allow passing in the tmpdir to use.

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Migrated from [LUCENE-5655](https://issues.apache.org/jira/browse/LUCENE-5655) by Ryan Ernst (@rjernst)

Locate the Hunspell dictionary and search suggester code that construct OfflineSorter, then inspect the OfflineSorter constructor they currently use. Add constructor options for the temporary directory in both components, and verify that callers can select the directory rather than relying on java.io.tmpdir.

Written by the indexing model from the issue text.