opencl: add cumsum op (llama/18981)

* OpenCL: add CUMSUM op support

* remove unused argument

* opencl: refactor cumsum

* opencl: refactor

* opencl: refactor tmp buffer

* opencl: adjust max number of subgroups

* opencl: fix whitespace

* opencl: fix global size when cumsum the tmp buffer

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Co-authored-by: Li He <lih@qti.qualcomm.com>