feat: Improve fill_histogram into a cython function with 13.83x speed up for burst mode

- Original function Single Cell:
Average time: 1.879472 seconds
Min time: 1.874208 seconds
Max time: 1.882767 seconds

- Cython function Single Cell:
Average time: 0.603006 seconds
Min time: 0.602453 seconds
Max time: 0.603634 seconds

Speedup: 3.12x

- Original function Burst Mode:
Average time: 17.192991 seconds
Min time: 17.174598 seconds
Max time: 17.211236 seconds

- Cython function Burst Mode:
Average time: 1.242232 seconds
Min time: 1.230240 seconds
Max time: 1.258492 seconds

Speedup: 13.84x