Don't assume host is wildcard if not provided

This change ensures that while parsing a package, we require an explicit
wildcard in the queries->intent->data->host field. Prior to this change,
we were defaulting to wildcard when not provided. This resulted in,
e.g. someone trying to get visibility to just browsers actually getting
access to all packages that handle any web intent.

Fixes: 160868841
Test: atest AppEnumerationTests IntentFilterTest
Change-Id: I771845467928b6655fe19efe89bd2ca548dca6e5