Add GEMM-based standard SDPA benchmark #1635

Job	Run time
test-coreml / test-backend-macos (coreml, models) / macos-job	3m 12s
test-coreml / test-backend-macos (coreml, operators) / macos-job	18m 2s
test-coreml / test-backend-linux	0s
test-coreml / package-golden-artifacts	0s
	21m 14s

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