Add GEMM-based standard SDPA benchmark and fix custom_sdpa_out signature #1504

Job	Run time
test-qnn / test-backend-linux (qnn, models) / linux-job	7m 23s
test-qnn / test-backend-linux (qnn, operators) / linux-job	7m 23s
test-qnn / test-backend-macos	0s
test-qnn / package-golden-artifacts	0s
	14m 46s

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