Merge both MONAI Label Slicer Modules

[diazandr3s]

I see this MONAI Label Slicer Module version is quite similar to the one published in MONAI Label.

It causes less confusion/friction if we only have a single MONAI Label Slicer Module.

Depending on which model the user starts the server, the Slicer module will be automatically configured. Similar to what was done for the DeepEdit and Segmentation models.

Should this repo be only about the VISTA model?