Support manual supplement to command line for batch executor

[applio]

As suggested in the forum (https://forum.knime.com/t/failure-to-run-workflows-with-database-connector-oracle-from-jupyter-notebook/18579), it might provide future flexibility to expose a way to manually supplement the command line that invokes KNIME's batch executor on local workflows.

This raises questions: Is this a good general solution when the problem should otherwise be solved by adding formal support for missing functionality? Should the entirety of the command line be manipulatable instead of merely permitting a supplement tacked on the end? Will enough users find it reasonably easy to come up with their own manual supplements to the command line?

[applio]

Commit b1616eba077b40dfb2074b960e50517fead5d0bc in branch enh_supplemental_cmdline explores this idea.