Define command line interface

[finsberg]

Just making an issue so that we can define a scope for the command line interface.

I think have a tool that can be used only as a CLI tool would be very useful. For example having a way to easily inspect a nift file, e.g

mri info file.nii.gz

(with mri being the entry point and info a subcommand would be nice).
I could also be nice to have a way to convert a file to a different format or even visualize it (but we could make a separate issue for this I think).

What I wold like to discuss here is the backend used for the command line interface. In my opionion there are three main choices: argparse, click or typer. I think we should also add colors using rich since that will make the experience much better.

I have no strong opinions other that reducing the amount of "magic" going on😊

[cdaversin]

I agree. click was used in gMRI2FEM which works well. But maybe the fewer dependencies the better, and in that case I would rather choose argparse (i.e. the only option in Python standard library)