Improve hierarchy of arguments passed to launcher

https://github.com/ansys/pyfluent/pull/5323#discussion_r3805477041

Sometimes we face issues like this where we need trade-offs. If we design properly we can handle cases in a hierarchical manner. Decide in future the design for resolution to these kinds of issues and implement.

Start by reading the discussion in PR #5323, especially comment discussion_r3805477041, to understand the argument trade-offs and the proposed hierarchy. The issue provides no file or test entry point; done means agreeing on a resolution design for launcher arguments and implementing it with suitable coverage.

Written by the indexing model from the issue text.