Split YUV & RGB Buffers Into Arrays

[jnnks]

The macro turned into many conditional jumps due to range checks.
This PR uses a more "rusty" syntax and removes many of the bound checks.

RUSTFLAGS='-C target-cpu=native' cargo +nightly bench convert_yuv_to_rgb


before:
test convert_yuv_to_rgb_1920x1080  ... bench:   5,080,432.75 ns/iter (+/- 188,360.31)
test convert_yuv_to_rgb_512x512    ... bench:     639,837.89 ns/iter (+/- 32,349.89)
test convert_yuv_to_rgba_1920x1080 ... bench:   5,477,576.50 ns/iter (+/- 691,816.61)

after:
test convert_yuv_to_rgb_1920x1080  ... bench:   2,660,560.60 ns/iter (+/- 170,850.83)
test convert_yuv_to_rgb_512x512    ... bench:     352,246.05 ns/iter (+/- 41,074.52)
test convert_yuv_to_rgba_1920x1080 ... bench:   2,524,497.02 ns/iter (+/- 158,960.58)

edit: wrong convert_yuv_to_rgba_1920x1080 number

[ralfbiedert]

Nice, thanks!