Continuous batching refactor

[remi-or]

This PR refactors the files related to continuous batching and changes a few parts of the logic:

• the way the max_batch_tokens and num_blocks is computed;
• the static inputs of the CB are now sliced to avoid passing an arbitrary amount of padding in the forward
• the example file for CB has been reworked to allow for more parametrization

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[ArthurZucker]

nice 🚀

[ArthurZucker]

Let's go 🚀