[FTS] QueryString syntax doesn't have short way to perform exact numeric equality search

A query string query to look for an exact numeric value needs to use a bounded approach, using both '<=' and '>=' numeric range operators. For example, for the a beer-sample FTS index looking for beers with a numeric abv field value of 6...

+abv:>=6 +abv:<=6

Note, the above approach also might not work as expected if there are more operators in the query string.

On what's going on... a search for "+abv:6" (I think) performs a default (probably text) analysis on the "6", leading to a text-oriented term search instead of an encoded numeric term search.

One possible proposed syntax might be "+abv:=6", but not sure of the implications of that. Should probably look at lucene syntax to see what they do.