Improve vision models
# What does this PR do?

This PR improves the vision models by:
- removing `to_2tuple`
- sanity checking whether the channel dimension of pixel values provided to the model match with `config.num_channels`
- replacing hardcoded 3 with `config.num_channels` for `xxxForMaskedImageModeling` models (fixes #17727) 
- replacing hardcoded 3 by `config.num_channels` in Flax models (ViT, BEiT)

To do:

- [x] ViT
- [x] BEiT
- [x] DeiT
- [x] Swin
- [x] PoolFormer
- [x] DPT
- [x] YOLOS
- [x] ViLT
- [x] GLPN
- [x] DPT
- [x] Data2VecVision
- [x] MaskFormer
- [x] ViTMAE
- [x] TF and Flax implementations
- [x] Corresponding test files
- [x] add more Copied from statements (e.g. DropPath)
_The documentation is not available anymore as the PR was closed or merged._