metal : add opt_step_adamw and op_sum (#16529) #21

Job	Run time
ubuntu-22-vulkan	4m 41s
ubuntu-22-cpu (x64, ubuntu-22.04)	2m 23s
windows-sycl	11m 11s
macOS-arm64	1m 36s
windows (vulkan, x64, -DGGML_VULKAN=ON, ggml-vulkan)	4m 54s
windows-cpu (arm64)	2m 13s
windows (opencl-adreno, arm64, -G "Ninja Multi-Config" -D CMAKE_TOOLCHAIN_FILE=cmake/arm64-window...	3m 38s
windows-cuda (12.4)	52m 29s
windows-cpu (x64)	3m 23s
windows-hip (radeon, gfx1151;gfx1200;gfx1201;gfx1100;gfx1101;gfx1102;gfx1030;gfx1031;gfx1032)	46m 27s
ios-xcode-build	15m 36s
macOS-x64	3m 48s
release	1m 46s
	2h 34m 5s

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