getResults with numeric indexes for fields

When executing a simple query with field names in SELECT clause, it is not possible to map field to numeric indexes.

This is an example that i would imagine to be useful:

SELECT c.id AS 0, c.name AS 1, l.text AS 2 FROM Category c LEFT JOIN c.label l

Thus, the resulting results could be numeric indexed array. It is useful for many situations: when working with an API which expects such arrays, or when using list to assign result fields to variables directly.

Query::HYDRATE_SCALAR does not achieve this, as one could think at first glance.