Added type hints for Pytorch Marian calls
As the title suggests, this PR adds type hints to the PyTorch Marian calls. (#16059 )

@Rocketknight1 
_The documentation is not available anymore as the PR was closed or merged._<|||||>@patil-suraj Hm, do I need to change the BART too for consistency?  
```
src/transformers/models/marian/modeling_marian.py: copy does not match models.bart.modeling_bart.BartAttention at line 144
src/transformers/models/marian/modeling_marian.py: copy does not match models.bart.modeling_bart.BartEncoderLayer at line 289
src/transformers/models/marian/modeling_marian.py: copy does not match models.bart.modeling_bart.BartDecoderLayer at line 356
src/transformers/models/marian/modeling_marian.py: copy does not match models.bart.modeling_bart.BartForCausalLM at line 1529
src/transformers/models/pegasus/modeling_pegasus.py: copy does not match models.marian.modeling_marian.MarianSinusoidalPositionalEmbedding at line 109
src/transformers/models/roformer/modeling_roformer.py: copy does not match models.marian.modeling_marian.MarianSinusoidalPositionalEmbedding at line 73
Run `make fix-copies` or `python utils/check_copies.py --fix_and_overwrite` to fix them.
```

Running `make fix-copies` basically reverts all my changes. 
<|||||>Hi @clefourrier, sorry for the delay! We will indeed need to make changes to BART to make the tests work - but we already have an existing BART PR here: https://github.com/huggingface/transformers/pull/16270. Probably the easiest thing to do is:

1. Wait until we merge that PR
2. If any changes in Marian are still needed, rebase your current PR onto it (make sure to force push afterwards!)
3. Check tests again afterwards<|||||>Hi @Rocketknight1 , perfect! Can you ping me once the BART PR is merged then?<|||||>@clefourrier It was just merged about half an hour ago! Take a look - if any changes are needed, you'll probably need to pull changes from upstream to the master branch of your fork, and then rebase (with force push!) onto that.<|||||>@Rocketknight1 Well, it seems the last failures comes from children archs (pegasus and roformer) - do they have their own PR? 