Add support for solr.TrieDateField

From the [`solr.TrieDateField` documentation][1]:

> An extension of `DateField` that supports the same values and syntax, but
> indexes the value more efficiently using a numeric `TrieField` under the
> covers.

This simply reuses the existing `DateFieldHandler`.

[1]: https://lucene.apache.org/solr/4_7_0/solr-core/org/apache/solr/schema/TrieDateField.html