Extend PgUtil.streamGet() to support manual selection of a set of columns

The PgUtil.streamGet() may be used for some exceptionally large data sets.
The current design does not seem performant resource-wise (memory consumption, network bandwidth, and to some extend time).
This happens because the entire jsonb appears to be return from the database to the backend module before it casts/converts/maps that response to some smaller object.

Ideally, provide a way to:

• Get only a selection of some fields, such as hrid.
• Get that response without object mapping.
• Maintain stream support.
• May involve improving *.raml functionality to designate non-object results.
• Consider additional actions on fields, such as select encode((jsonb->>'id')::bytea, 'base64') from instance;.
• Potentially get the table columns and not just jsonb keys/properties (get 'id' instead of 'jsonb->id') for performance reasons.

This potentially blocks MODINVSTORE-439, but can alternatively be considered tech-debt to instead not block and utilize the currently functional but less performant implementation of PgUtil.streamGet().