Better benchmark for cpu

[EricLBuehler]

See #28, better benchmarking for CPU

[EricLBuehler]

cpu_graph_matmul_64x64 time: [58.646 µs 59.099 µs 59.706 µs]
Found 11 outliers among 100 measurements (11.00%)
1 (1.00%) low severe
5 (5.00%) low mild
1 (1.00%) high mild
4 (4.00%) high severe

cpu_graph_matmul_128x128
time: [341.67 µs 343.09 µs 344.49 µs]
Found 5 outliers among 100 measurements (5.00%)
1 (1.00%) low severe
2 (2.00%) low mild
2 (2.00%) high mild

cpu_graph_matmul_256x256
time: [805.95 µs 808.13 µs 810.33 µs]
Found 7 outliers among 100 measurements (7.00%)
2 (2.00%) low mild
3 (3.00%) high mild
2 (2.00%) high severe

candle_matmul_64x64 time: [37.669 µs 38.294 µs 38.970 µs]
Found 18 outliers among 100 measurements (18.00%)
1 (1.00%) low severe
1 (1.00%) low mild
4 (4.00%) high mild
12 (12.00%) high severe

candle_matmul_128x128 time: [338.73 µs 339.75 µs 340.83 µs]
Found 7 outliers among 100 measurements (7.00%)
1 (1.00%) low severe
2 (2.00%) low mild
3 (3.00%) high mild
1 (1.00%) high severe

candle_matmul_256x256 time: [895.69 µs 902.61 µs 909.66 µs]
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) low mild