R1:5263d5d59030

Custom integer fields: fix search by array of possible values

Summary:
This minimal changes seems the natural expansion of this search function,
that "seems" designed to only search with a single value, but the backend
is designed to receive an array of possible values.

Look at the same method in PhabricatorStandardCustomFieldLink that already
works also for array inputs.

To get extra confidence look at the method withApplicationSearchContainsConstraint()
that works perfectly with arrays (to be honest…