Make "psms" tuple used for output a named tuple

[VarunAnanth2003]

Primarily concerns model.py and ms_io.py.
Currently, how model output from model.py is passed into ms_io.py is confusing. ms_io.py has a "psms" attribute that is appended to by on_predict_batch_end. The below chunk of code is an example of how the "psms" tuple is appended to ms_io.py currently.

Each of these fields should be given a name within a named tuple, and this named tuple should be used to pass information to ms_io.py instead of how it is being done now.

[bittremieux]

Or rather a dataclass instead, for added flexibility.

I agree that this would be a good tweak to make the code easier to understand: define a Psm dataclass that has attributes for the information needed for the mzTab export, create those objects during prediction, and ultimately write it to the output file.

@Lilferrit Can you look into tackling this?