ggml-metal: FWHT kernel for metal backend (#25924)
* metal fwht wip
* shape guard and formatting
* formatting
* Formatting and typos
Co-authored-by: YiChen Lv <63285796+forforever73@users.noreply.github.com>
* fix narrowing issue
Co-authored-by: YiChen Lv <63285796+forforever73@users.noreply.github.com>
* cont : minor style
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Co-authored-by: YiChen Lv <63285796+forforever73@users.noreply.github.com>
Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
