Update `constants` import to use module-level access #1172 (#2453)
* Update `constants` import to use module-level access (#1172)
* Update constants import to use module-level access #1172 #2453
* Update constants imports with backward compatibility #1172, #2453
* Update fastai_utils.py
* Update hf_api.py
* remove unecessary changes
---------
Co-authored-by: Lucain Pouget <lucainp@gmail.com>