8627 perceptual loss errors out after hitting the maximum number of downloads

[virginiafdez]

Fixes #8627.
Moves the perceptual loss code to MONAI repository https://github.com/Project-MONAI/perceptual-models and the checkpoints to Huggingface.

Description

This PR changes and simplifies the torch.hub loading process and gets the models from Huggingface lirbary.
A few sentences describing the changes proposed in this pull request.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• [N/A] New tests added to cover the changes.
• [N/A] Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.