Lite's collectives feature

[carmocca]

What does this PR do?

Fixes (keep open) #7534 for Lite
Fixes #13821.

TODO:

• Integrate into the strategies
• Clean up random distributed files (marked with FIXME).
• Docstrings
• Tests

Open questions:

• Should we support https://github.com/pytorch/pytorch/blob/master/torch/distributed/nn/functional.py?

Constraints:

• Async operations are not supported. They can only be implemented for PyTorch but they break the LSP with the Collective as they would require a generalized return in the base class.

Does your PR introduce any breaking changes? If yes, please list them.

None, as the new Lite is unreleased.

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[carmocca]

In the spirit of #12786, we should make these local imports

[gitguardian]

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