Use u64 in Raders twiddle calculations

[HEnquist]

No description provided.

[ejmahler]

Looks like maybe the commands available to the CI are different somehow, meaning the script we've been using to test webassembly doesn't work.

That probably doesn't need to block this PR, since I'm not worried about this PR breaking webassembly SIMD tests

[HEnquist]

Yes something must have changed very recently, the run from just a few days ago finished just fine.

[LukasWuethrich]

What's next?
I would like to help, but my knowledge is probably insufficient. But let me know if there's anything I can do to contribute.

[HEnquist]

We need to figure out why the wasm test fails. For some reason the command wasm-pack test --node --lib --features wasm_simd no longer works on nightly. The jobs with beta and stable were cancelled so I don't know if they would have failed too.
Specifically it complains about the --lib argument. A good start would be to check if it has been removed or renamed.

[ejmahler]

The --lib argument itself was a workaround for the fact that wasm-pack was incorrectly picking up some non-public comments as doctests. So I just removed the backticks from those comments and removed the --lib argument.