Add support for CUMSUM and TRI for CUDA. (llama/17584)

Add support for CUMSUM and TRI for CUDA. (llama/17584)

* Add support for CUMSUM and TRI for CUDA.

* Minor optimizations.

* Correct warp_prefix_inclusive_sum in float2 variant to return float2

* Optimize TRI

* Whitespace

* Fix strides.

* Implement double loop

* Whitespace

* Fix HIP compilation bugs

* Optimizations + big case performance tests

* Implement using CUB with fallback to custom kernel

* Remove error message.

* Fixes from code review

* Comment out CPU-unsupported F16/BF16 cases to fix CI

* Fine, you win :P

* Fix last cast, use NO_DEVICE_CODE and GGML_UNUSED_VARS

* Vary warp-size based on physical warp size

* Add GGML_UNUSED_VARS in tri as well

* Use constexpr and call prefix_inclusive with warp_size template param

* Update ggml/src/ggml-cuda/cumsum.cu

Co-authored-by: Johannes Gäßler <redacted>
* Apply suggestions from code review

Co-authored-by: Johannes Gäßler <redacted>
* Change to tid % warp_size

* Fix strides; hardcode mask; add ggml_lane_mask_t

* Missing renames, remove unused get_warp_mask(), explicit calls to ggml_cuda_info()

* Too hasty...

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Co-authored-by: Johannes Gäßler <redacted>