Inference slicer batching

[LinasKo]

Description

PR for inference slicer with batching. If batch_size is set, collections of slices are passed to the model.
Note that user need to define a callback that can accept list of images.

Still using threads if worker_threads > 1 (both batches and threads can be used simultaneously)

Previous PR, auto-closed during rewrite: #1108

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How has this change been tested, please provide a testcase or example of how you tested the change?

https://colab.research.google.com/drive/1cfqBss7n-jc6VyKdjJ1AN9TnOBjdYQwZ?usp=sharing

Any specific deployment considerations

Docs

• Docs updated? What were the changes:

[CLAassistant]

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[LinasKo]

I've seen multiple CLA-related updates just now. Let's sort it out when I'm back from my trip.

P.S. It may also be due to me changing my github email a week ago.