Previously, we deduced the range type from the range objectclass
and filled in virtual attribute in post_callback phase.
Having a ipaRangeType attributeType in schema, we need to fill
the attribute values to ranges created in previous IPA versions.
The plugin follows the same approach, setting ipa-local or
ipa-ad-trust value to the ipaRangeType attribute according
to the objectclass of the range.
Part of https://fedorahosted.org/freeipa/ticket/3647
