Move common image processing methods to BaseImageProcessor
# What does this PR do?

Moves out the `rescale` and `normalize` methods of the image processors to the BaseImageProcessor class, which all the image processors inherit from. 


Reason for moving `rescale` and `normalize`:
* Standard image processing steps
* Used by (almost) all image processors 
* Few cases when the logic is model specific e.g. [ViVit](https://github.com/huggingface/transformers/blob/f9cc333805c47665c6afee8b5867931e54abe0c6/src/transformers/models/vivit/image_processing_vivit.py#L196). 


Reason for not moving other methods: 
* Many require model specific preparation before calling the transforms function. For example, `resize` has different logic across many models e.g. [1](https://github.com/huggingface/transformers/blob/f9cc333805c47665c6afee8b5867931e54abe0c6/src/transformers/models/beit/image_processing_beit.py#L142), [2](https://github.com/huggingface/transformers/blob/f9cc333805c47665c6afee8b5867931e54abe0c6/src/transformers/models/detr/image_processing_detr.py#L865), [3](https://github.com/huggingface/transformers/blob/f9cc333805c47665c6afee8b5867931e54abe0c6/src/transformers/models/vilt/image_processing_vilt.py#L196)
* Some methods aren't universal to all image processors and don't make sense to add to all image processors e.g. [reduce_label](https://github.com/huggingface/transformers/blob/f9cc333805c47665c6afee8b5867931e54abe0c6/src/transformers/models/beit/image_processing_beit.py#L235)
* Some will be moved in future e.g. center_crop but this requires a bit more work outside the PR scope


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- [ ] Did you write any new necessary tests?
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