Add API to get devices of offload states (#6586)
This PR adds an API `deepspeed.runtime.zero.offload_states
get_state_devices`, which gets devices of offload states as suggested in
this
[comment](https://github.com/microsoft/DeepSpeed/pull/6011#issuecomment-2358068777).
We could lift this up to `deepspeed.utils` but would need to resolve a
circular import: User code -> `deepspeed.utils` ->
`deepspeed.utils.offload_states` -> `deepspeed.runtime.zero` ->
`deepspeed.runtime.zero.partition_parameters` -> `deepspeed.utils`
This will require a significant refactoring as long as we have
`OffloadStateTypeEnum` in `deepspeed.runtime.zero`.
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Co-authored-by: Logan Adams <114770087+loadams@users.noreply.github.com>
Co-authored-by: Olatunji Ruwase <olruwase@microsoft.com>
