Add DICOM series conversion to NIfTI

[ZviBaratz]

The interface should allow configuring the location of dcm2nii or some other conversion program and using it on a DICOM series when needed for an analysis or requested by a user (there should be some kind of button or configuration that creates and keeps a reference for a NIfTI version).

[ZviBaratz]

Currently, dcm2niix is used (program location configuration through .env file) and each series directory is created with a 'DICOM' directory by default. If and when the series is converted to NIfTI, another directory is created with the new appropriate format name.