Add type annotations for Rembert/Splinter and copies
Splinter and Rembert (Torch) type annotations.
Dependencies on Bert (Torch).
Raw files w/o running make fixup or make fix-copies

#16059
@Rocketknight1 
By the way, GitHub is having some issues right now and tests may not be running. Feel free to continue with the PR, but we'll need to wait for them to come back before we can merge!<|||||>_The documentation is not available anymore as the PR was closed or merged._<|||||>Tests are back, going to try fixing copies etc. now, one sec!<|||||>Is this a private file? This was the main error I was receiving after run fix-copies (from the build strack trace)

```
self = <module 'transformers.models.template_bi' from '/home/runner/work/transformers/transformers/src/transformers/models/template_bi/__init__.py'>
module_name = 'modeling_template_bi'

    def _get_module(self, module_name: str):
        try:
            return importlib.import_module("." + module_name, self.__name__)
        except Exception as e:
            raise RuntimeError(
                f"Failed to import {self.__name__}.{module_name} because of the following error (look up to see its traceback):\n{e}"
>           ) from e
E           RuntimeError: Failed to import transformers.models.template_bi.modeling_template_bi because of the following error (look up to see its traceback):
E           name 'Optional' is not defined```<|||||>Ah, I see the problem now! This error is in our template files, and yes, it can be hard to spot, because it only appears when one of our tests tries to generate a new class from the template. Give me a second and I'll see if I can fix it!<|||||>I see. Definitely scratched my head at these for a while - Thanks so much for your help!