Add Universal Segmentation class + mapping
# What does this PR do?

This PR adds the `AutoModelForUniversalSegmentation` class and corresponding mapping. Models that can be added to this mapping include DETR, MaskFormer, Mask2Former and OneFormer.

To do:

- [x] update pipeline

@sgugger for some reason make fixup complains:

```
Traceback (most recent call last):
  File "/Users/nielsrogge/Documents/python_projecten/transformers/utils/check_repo.py", line 827, in <module>
    check_repo_quality()
  File "/Users/nielsrogge/Documents/python_projecten/transformers/utils/check_repo.py", line 816, in check_repo_quality
    check_models_are_in_init()
  File "/Users/nielsrogge/Documents/python_projecten/transformers/utils/check_repo.py", line 369, in check_models_are_in_init
    raise Exception(f"The following models should be in the main init: {','.join(models_not_in_init)}.")
Exception: The following models should be in the main init: MaskFormerForUniversalSegmentation.
```
I think the error message is pretty clear on what to do. The model would also need to be added to the doc page of maskformer if we go through with this.

I'm not convinced we should however. While adding a new auto-model API could make sense (I'd wait to have more than one model though), renaming the model class a year after the model has been released is not something we should do (the same way we keep `GPTLMHeadModel` for instance). <|||||>_The documentation is not available anymore as the PR was closed or merged._<|||||>I'm unsure why you keep changing more of the `MaskFormerForInstanceSegmentation`. I think I may have been unclear in my previous comments. I am against changing that name in a model that has been around for 10 months now, for the same reason we did not change the name of `GPTLMHeadModel` or `BertLMHeadModel` even if those are not ideal.<|||||>@sgugger I'll keep the old names, but add them to the same (new) mapping.