hexagon: support for backend sampler (#29502)
* hex-topk: trying to improve/cleanup the pipeline
* hex-sampling: add STEP op
* hex-sampler: add SUM op
* hex-sampler: update CPY to support sampling cases
* hex-binary: add support for chunking to handle large logits
* hex-argmax: super basic version of ARGMAX
* hex-binary: support for scalars in extended buffers
* hex-binary: fix wrong indexing for dim 1 broadcasts across dim 2 slices
* hex-argsort: fix missing header
* hex-sampler: cleanup dma usage in the sampler related ops, and binary
* hex-build: disable autovectorizer, it is better to use explicit hints for critical loops
* hex-binary: fix perf regression due to is_1d fallback
* hex-ops: update supported ops
