Download script doesn't indicate number or total size of models that will be downloaded

[tazlin]

Currently, new worker operators who start the worker script for the first time may have little idea of how much disk space is about to be used.
There should be:

• a clear progress bar for the total progress across all model types, in gigabytes
• a clear progress bar for the total progress for the current model type (codeformers, compvis, etc), in gigabytes
• See also FR: Check available disk space before downloading models #267 which could be tackled at the same time