PR #11405: [gpu] Add address computation fusion for RS->DUS pattern
PR #11405: [gpu] Add address computation fusion for RS->DUS pattern

Imported from GitHub PR https://github.com/openxla/xla/pull/11405

This patch recognizes a reduce-scatter operation that is used by a dynamic-update-slice operation. It then fuses this operation to an address-computation fusion.
For example, the following pattern is extracted to a fusion:
```
reduce-scatter = f16[64,128] reduce-scatter(%p0), channel_id=64, replica_groups={{0,1}}, use_global_device_ids=true, dimensions={0}, to_apply=add
dynamic-update-slice = f16[128,128] dynamic-update-slice(%p1, reduce-scatter, %p3, constant.718)
``` 
Copybara import of the project:

--
2c26d292ac1cbe8742b773228caf4a21d8bb6d36 by Shraiysh Vaishay <svaishay@nvidia.com>:

[gpu] Add address computation fusion for RS->DUS pattern

Merging this change closes #11405

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/11405 from shraiysh:address_computation 2c26d292ac1cbe8742b773228caf4a21d8bb6d36
