Remove headers of the files

[juliendenize]

In v0.4.1 the license was changed to CeCILL-C and the copyright was transferred to CEA as it was first developed in my spare time and as part of my diploma thesis and now as part of my job.

For this release, I modified the header of every files to mention the following:

# @Copyright: CEA-LIST/DIASI/SIALV/ (2023-    )
# @Author: CEA-LIST/DIASI/SIALV/ <julien.denize@cea.fr>
# @License: CECILL-C

With some of them also crediting Torchvision by adding:

#
# Code partially based on Torchvision (BSD 3-Clause License), available at:
#   https://github.com/pytorch/vision

We should consider removing these mentions to get rid of templates:

• The COPYRIGHT file already contains a template that people can use to refer to Torchaug and that contains the credits to Torchvision. Torchvision is also credited in the README that is packaged along the code on Pypi.
• Is there a legal value of such mentions ? and even if yes, does it have to be attached to each file when the LICENSE is packaged ?

[juliendenize]

Another possibility is to add in the CI a check for the headers to be correctly setup for all files;