Add `no_trainer` scripts to pre-train Vision Transformers
# What does this PR do?

Add scripts to pre-train Transformer-based Vision models without using the Trainer class.

Fixes #20053
Fixes #20412 
This PR completes the stalled PR #20412.

## Who can review?

@amyeroberts @NielsRogge @sgugger

_The documentation is not available anymore as the PR was closed or merged._<|||||>@NielsRogge As per https://github.com/huggingface/transformers/pull/20412#issuecomment-1370792519, I have made a comparison notebook running both the trainer.py and no_trainer.py scripts on a small dataset. It can be viewed [here](https://colab.research.google.com/drive/1er4n0_AoQZU-OtXZPla3i-rJ38apA_zh?usp=sharing).

Both the scripts progress similarly.<|||||>Thanks a lot @awinml! I'll assign core maintainers for a final review.