Add ConvNeXt-V2 Model
# What does this PR do?

Adds ConvNeXt-V2 to transformers.
original repo: https://github.com/facebookresearch/ConvNeXt-V2
paper: https://arxiv.org/abs/2301.00808

## Before submitting
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- [x] Did you write any new necessary tests?

@alaradirik 

It does look like the model code is exactly the same at a first glance (saw everything is copied from ConvNext). If that is the case, yes to re-using the code of ConvNext, but if we need to make modifications in the convnext modeling file, we should add ConvNext V2 as a new model like in the PR.<|||||>> It does look like the model code is exactly the same at a first glance (saw everything is copied from ConvNext). If that is the case, yes to re-using the code of ConvNext, but if we need to make modifications in the convnext modeling file, we should add ConvNext V2 as a new model like in the PR.

Yes, the code is almost the same, but it adds a Global Response Normalization (GRN) module and removes the layer_scale_parameter from the ConvNeXtV2Layer. Makes more sense to add it as a new model then.

CC @IMvision12 <|||||>Thanks for the review @alaradirik I will address all comments!<|||||>_The documentation is not available anymore as the PR was closed or merged._