Replace HashBytes manual array impl with min_const_generics

[BlackHoleFox]

When going for a 128 byte image hash, I noticed that the size wasn't actually implemented, even though the doc comment said as such. So, instead of just adding more lengths I tried to just switch it to min_const_generics instead since its been on stable for a while now.

If you prefer not to make the MSRV so high I can drop this commit and just add the extra array implementations.