Create simple test.py inference script

[plbenveniste]

similar to https://github.com/ivadomed/model_seg_mouse-sc_wm-gm_t1/blob/main/test.py, but compatible with nnUnet:

• input NIfTI file
• create nnUnet compatible folder structure
• run nnUnet CLI as system call
• reorganize file
• delete temp files
• done

Related to #38

[plbenveniste]

Code based on run_inference.py.

[jcohenadad]

Code based on run_inference.py.

this URL points to a code in a branch, which will likely be deleted once the branch is merged (hence will give a 404 error in the futur), so I suggest to instead point to a code in a 'master' version of git. I think that the code in question is this one: https://github.com/ivadomed/utilities/blob/main/packaging/run_nnunet_inference.py