Ensure naming consistency with all networks and losses

[justusschock]

We should take care of the naming consistency.

here is my Proposal:

• Everything that can be used directly (either a loss or a network with a closure should contain the backends name (for now, we only have PyTorch here, but we have to decide on whether to name it torch (as the backends name while checking for it) or PyTorch).

• Everything that cannot be used directly must not contain this kind of suffix, but should not be included in any kind of __init__.py to avoid name confusion.

What do you think of this @delira-dev/vision ?