Improve integration of TotalSegmentator with MONAI Deploy

[tomaroberts]

TotalSegmentator is a Python-based app, which means it should be possible to integrate with the MONAI tools.

For example:

• Use MONAI Deploy DICOM conversion tools rather than calling dcm2niix via subprocess command
• Call TotalSegmentator within the operator rather
• Use the MEMORY-based functionality in MONAI Deploy rather than DISK, which should be faster

nb: nice-to-have rather than essential enhancements, at this stage

[tomaroberts]

Commit 44c86b2 within #21 implements DICOM parsing with MONAI Deploy DICOMSeriesSelectorOperator.