sycl: add RMS_NORM_BACK operation support (#16808)

sycl: add RMS_NORM_BACK operation support (#16808)

* sycl: add RMS_NORM_BACK operation support

* sycl: rms_norm_back: add dual reduction paths (FP64 and FP32) and savepoint before further changes

* sycl: add RMS_NORM_BACK support

Implement RMS_NORM_BACK for the SYCL backend using FP32 compensated parallel reduction. Minimal docs updates (ops.md / SYCL.csv).

* revert: restore .gitignore and tools/run/CMakeLists.txt to upstream

* revert: restore tests/CMakeLists.txt to upstream

* sycl: optimize rms_norm_back

* fix: restore SYCL.csv to correct state with RMS_NORM_BACK support

* Update ggml/src/ggml-sycl/norm.cpp

Co-authored-by: Neo Zhang Jianyu <redacted>
* fix: remove trailing whitespace and add missing newline (EditorConfig)

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Co-authored-by: Neo Zhang Jianyu <redacted>