Introduce breakpoint API (#1940)
* early stopping
* Fix tests
* Works on multi-gpu, uncomment
* Rm reset
* Check for >=1
* equal
* Trigger
* Fix test
* Update docs/source/concept_guides/deferring_execution.md
Co-authored-by: Benjamin Bossan <BenjaminBossan@users.noreply.github.com>
* Explicit example loop
* Set to zero, not None
* rename test
* Check again to ensure it's been reset
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Co-authored-by: Benjamin Bossan <BenjaminBossan@users.noreply.github.com>
