modeldownload: Use webui_streamlit.yaml to update models

[irgolic]

Description

Please include:

• relevant motivation
• a summary of the change
• which issue is fixed.
• any additional dependencies that are required for this change.

The modeldownload.py script is outdated (doesn't use the new paths), and there's a need for a script that downloads all models. It has been fixed to read the model_manager config in streamlit_webui.yaml, and download models to the correct locations.

Checklist:

• I have changed the base branch to dev
• I have performed a self-review of my own code
• I have commented my code in hard-to-understand areas
• I have made corresponding changes to the documentation