ID type with bitwidths

[teburd]

Perhaps it would be better, once const ints are allowed for type params, that Flaken use those for creating specific types of Flake generators based on bitwidths. Even better if at compile time these things failed should the bitwidths not match up to the resulting type(s).

32, 64, and 128 bit width flake id generators would be really nice as well

something like...

let flake = Flaken::<u64, 40, 12, 12>::default()

[teburd]

Perhaps with typenum this is doable now

let flake = Flaken::<u64, U40, U12, U12>::default();

[teburd]

So seeing as const generics are coming, the typenum hack will not be needed and I can update this with bitwidths as type params soonish I hope