FrelonSegmenterGui: Extract choose_frame and segment_frame as functions

[loichuder]

For #358

@abmajith did some progress on #358 and would need to reuse some part of the FrelonSegmeterGui but without the Gui.

The two methods we are interested in are the choose_frame method and the segment_frame method. These are not tied to the ipywidgets so we could extract them to reuse them outside of the FrelonSegmeterGui which is tied to Jupyter.

Would that be ok if we extract the relevant code in functions ? We could them call them outside of FrelonSegmeterGui without any functional change to this class ?

Of course, we are happy to discuss this further if you think of another strategy 👍

[jonwright]

Extracting choose_frame is a good refactoring as it seems to be there twice, for both FrelonSegmenterGui and SegmenterGui.

For segment_frame - this is just calling frelon_peaksearch.worker which is a class with many attributes that come in via the options from the gui. I wonder if you are better off just creating your own worker instance and calling peaksearch on it with your own options? Or maybe we add the function you need within frelon_peaksearch.py.

If you can send a pull request then I don't see any reason not to merge it? Thanks!

[loichuder]

Thanks for the encouraging words @jonwright !

@abmajith did a MR (#374) for the choose_frame extraction and we are working on the rest 👍