Leverage filtering of cases from the initial configuration window

[maxradx]

Is your feature request related to a problem? Please describe.
Depending on the work, a user that works with MRI or Scans might want to select only subset of volumes in a given datasets (e.g. only T2w sagittal MRI images or T1 axial images).

Describe the solution you'd like
To optimize processing, the user should have the ability to configure such options in the initial configuration window (and add conditions that are related to the organization of the dataset).

Additional context
In WorkFiles class.py, the function filter_working_list() can be used to add any options for filtering the Cases extracted from the volumes folder. This function is intended to be customized from the initial configuraiton set up window.