Pathfind Add N1QL Support for Collections

Goal is to author a draft sdk-rfc and changeset that implements N1QL collections support.

One goal of collections is to simplify the 'keyspace' in the grammar. This is done by allowing N1QL to use `collection` as the target of the FROM clause disambiguating with a 'scope' added as an HTTP parameter. See details in the parent CBD.

Set query_context REST API parameter