[Java API] Explore QST Impl

[nbauernfeind]

Devin demo'd the power and allure of https://immutables.github.io/. It looks pretty promising. Visitor pattern from Immutable QST to the BatchTable protobuf request should be straight forward.

The approach is not extensible for custom operations; but neither is batch -- one would need to plumb the custom operation through batch to be able to add the custom operation to the QST. The integration with batch is sufficient effort that the additional overhead to add it to the QST (if he/she cares) is a reasonably small amount of additional effort.

The goal here is to demo some form of a QST being constructed before the worker connection, connect to worker, instantiate QST, finally demo access to result table in QST. We need buy in from the larger group on the approach, before flushing out all operations.

Follow Up Task: #711
Epic: Java API #257