Improve performance using parallelized iter

[Neylix]

Improve performance using par_iter from rayon lib.
Benchmark on aggregate_public_keys
Same performance gain on aggregate_signatures

##### With input 1 #####
Name                                ips        average  deviation         median         99th %
aggregate parallel iter          2.29 K      436.72 μs     ±7.22%      430.67 μs      583.51 μs
aggregate sequential iter        2.25 K      445.18 μs     ±4.52%      443.94 μs      471.41 μs

Comparison:
aggregate parallel iter          2.29 K
aggregate sequential iter        2.25 K - 1.02x slower +8.45 μs

##### With input 3 #####
Name                                ips        average  deviation         median         99th %
aggregate parallel iter          1.66 K        0.60 ms    ±23.47%        0.54 ms        1.01 ms
aggregate sequential iter        0.79 K        1.27 ms     ±4.82%        1.26 ms        1.33 ms

Comparison:
aggregate parallel iter          1.66 K
aggregate sequential iter        0.79 K - 2.11x slower +0.67 ms

##### With input 5 #####
Name                                ips        average  deviation         median         99th %
aggregate parallel iter          1.21 K        0.82 ms    ±23.77%        0.92 ms        1.06 ms
aggregate sequential iter        0.48 K        2.08 ms     ±0.94%        2.07 ms        2.14 ms

Comparison:
aggregate parallel iter          1.21 K
aggregate sequential iter        0.48 K - 2.52x slower +1.25 ms

##### With input 10 #####
Name                                ips        average  deviation         median         99th %
aggregate parallel iter          955.18        1.05 ms     ±8.59%        1.03 ms        1.50 ms
aggregate sequential iter        243.30        4.11 ms     ±0.84%        4.11 ms        4.22 ms

Comparison:
aggregate parallel iter          955.18
aggregate sequential iter        243.30 - 3.93x slower +3.06 ms

##### With input 50 #####
Name                                ips        average  deviation         median         99th %
aggregate parallel iter          261.52        3.82 ms     ±6.92%        3.77 ms        4.52 ms
aggregate sequential iter         49.07       20.38 ms     ±0.63%       20.35 ms       21.11 ms

Comparison:
aggregate parallel iter          261.52
aggregate sequential iter         49.07 - 5.33x slower +16.55 ms

##### With input 100 #####
Name                                ips        average  deviation         median         99th %
aggregate parallel iter          140.59        7.11 ms     ±3.14%        7.10 ms        7.77 ms
aggregate sequential iter         24.62       40.62 ms     ±0.34%       40.60 ms       41.16 ms

Comparison:
aggregate parallel iter          140.59
aggregate sequential iter         24.62 - 5.71x slower +33.51 ms

##### With input 150 #####
Name                                ips        average  deviation         median         99th %
aggregate parallel iter           88.74       11.27 ms     ±5.62%       11.46 ms       12.51 ms
aggregate sequential iter         16.39       61.00 ms     ±1.13%       60.87 ms       66.62 ms

Comparison:
aggregate parallel iter           88.74
aggregate sequential iter         16.39 - 5.41x slower +49.73 ms

##### With input 200 #####
Name                                ips        average  deviation         median         99th %
aggregate parallel iter           66.21       15.10 ms     ±2.54%       15.03 ms       16.55 ms
aggregate sequential iter         12.46       80.29 ms     ±0.59%       80.37 ms       81.81 ms

Comparison:
aggregate parallel iter           66.21
aggregate sequential iter         12.46 - 5.32x slower +65.18 ms