Add type annotations for Rembert/Splinter and copies (#16338)

* undo black autoformat

* minor fix to rembert forward with default

* make fix-copies, make quality

* Adding types to template model

* Removing List from the template types

* Remove `Optional` from a couple of types that don't accept `None`

Co-authored-by: matt <rocketknight1@gmail.com>

templates/adding_a_new_model/cookiecutter-template-{{cookiecutter.modelname}}/modeling_{{cookiecutter.lowercase_modelname}}.py

@@ -25,6 +25,7 @@ import torch.utils.checkpoint
 from packaging import version
 from torch import nn
 from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss
+from typing import Optional, Tuple, Union
 
 from ...activations import ACT2FN
 from ...file_utils import (