Add support for "configuration" files

[smoia]

This moves both in favour of an easier management of the CLI and in favour of a quicker reusability of the pipeline,
also letting the centres that are interested (BCBL, NW, FIU, ...) to have a prepared setup to run phys2bids.
The idea is to be able to call phys2bids either with the commands that we know, or with a flag --config followed by a configuration file that gives all the arguments to phys2bids.
It could be a txt file, a yaml or json file, or simply a CLI bump to a file.
We should also save this file, so that further runs of phys2bids can use it to reproduce the same pipeline.

Possible Implementation

• Decide the type of file for the configuration (yaml or txt would be a good option!)
• Add a parser argument to accept it
• Add a function that reads the config file, but doesn't overwrite the options given as input in the CLI
• Add a function to export this configuration file

[vinferrer]

• We could actually put this config file to the folder code/conversion both when is introduced by the user and when the flags are manually inputted. This way a person can call manually phys2bids flags and then reused the generated config files for other recordings so they only have to change a few parameters