Remove Fuse from impl Merge for array

[yoshuawuyts]

Tracking issue: #22

Inlines the poll states on array::merge and removes the sort-based indexing. This results in a 3-10x speedups across the board:

compared to main branch

group                main                                   patch
-----                ----                                   -----
array::merge 10      3.25      4.2±0.26µs        ? ?/sec    1.00  1293.1±57.06ns        ? ?/sec
array::merge 100     9.41   376.3±25.42µs        ? ?/sec    1.00     40.0±1.13µs        ? ?/sec
array::merge 1000    9.54     40.0±1.72ms        ? ?/sec    1.00      4.2±0.06ms        ? ?/sec

compared to last release

❯ critcmp baseline patch  -f array::merge
group                baseline                               patch
-----                --------                               -----
array::merge 10      3.27      4.2±0.28µs        ? ?/sec    1.00  1293.1±57.06ns        ? ?/sec
array::merge 100     9.14   365.5±13.01µs        ? ?/sec    1.00     40.0±1.13µs        ? ?/sec
array::merge 1000    9.35     39.2±1.49ms        ? ?/sec    1.00      4.2±0.06ms        ? ?/sec