Add DPT hybrid
# What does this PR do?

Adds DPT Hybrid support to `transformers`

Do not merge until #20550 gets merged

cc @NielsRogge @sgugger @patrickvonplatten @patil-suraj 

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20612). All of your documentation changes will be reflected on that endpoint.<|||||>You should have opened your PR to go on the branch adding BiT and VitHybrid as the PR is not easy to review as it is.<|||||>Yes sorry :/  Let me open a PR on the other branch<|||||>Here is a much cleaner version of the PR: https://github.com/NielsRogge/transformers/pull/51 ;) <|||||>Closing in favor of https://github.com/huggingface/transformers/pull/20645