Configure certain classes with files for the command line case

[nicholasjng]

In user code, we can easily instantiate a reporter etc. with arguments, but on the command line, this does not work. Therefore, we have to use a different idea.

One possible is jsonargparse, which instantiates builtin and custom classes with arguments given on the command line. Other ideas are mostly related to reading static configuration from a file, for example .nnbench.yaml or even pyproject.toml with a tool.nnbench section.