* add internal /folder_paths route

returns a json maps of folder paths

* (minor) format download_models.py

* initial folder path input on download api

* actually, require folder_path and clean up some code

* partial tests update

* fix & logging

* also download to a tmp file not the live file

to avoid compounding errors from network failure

* update tests again

* test tweaks

* workaround the first tests blocker

* fix file handling in tests

* rewrite test for create_model_path

* minor doc fix

* avoid 'mock_directory'

use temp dir to avoid accidental fs pollution from tests