Reduce duplicate SQL parsing in Broker

SQL gets parse up to twice in brokerRequestHandler because there's 2 different endpoint to parse options and SQL into SQLNodes.

Propose to unify it and have request handler giving 2 APIs:
- one accepts JSON Request STRING;
- one accepts the parsed SQLNodeAndOption so that it doesn't get reparse.

Start at brokerRequestHandler and trace the two endpoint paths that parse options and SQL into SQLNodes. Compare the JSON Request STRING API with the parsed SQLNodeAndOption path; done means the request handler exposes both forms without reparsing SQL.

Written by the indexing model from the issue text.