Introduce Rayon for parallel iteration and sorting

• Use into_par_iter() before setting out to calculate scores and then filter by them

This represents a more efficient parallelism approach, with no mutex
or global state at top level.

ivy_files(kubernetes) time: [4.5800 ms 4.6121 ms 4.6467 ms]

change: [-55.056% -54.570% -54.133%] (p = 0.00 < 0.05)
Performance has improved.

ivy_match(file.lua) time: [1.1514 µs 1.1599 µs 1.1694 µs]

change: [+0.4116% +2.0753% +3.6710%] (p = 0.01 < 0.05)
Change within noise threshold.