Add benchmarks for transposed vs standard KV cache layout #1557

Job	Run time
test-xnnpack / test-backend-linux (xnnpack, operators) / linux-job	14m 17s
test-xnnpack / test-backend-linux (xnnpack, models) / linux-job	53m 6s
test-xnnpack / test-backend-macos	0s
test-xnnpack / package-golden-artifacts	3m 43s
	1h 11m 6s

Provide feedback