Support very large bigints

[dansteren]

Looks like we have a limitation on large numbers. While implementing #57 I called dfx canister call factorial fac '(50)' expecting the value 30_414_093_201_713_378_043_612_608_166_064_768_844_377_641_568_960_512_000_000_000_000n
and instead got the following error:

Error: The Replica returned an error: code 5, message: "IC0503: Canister rrkah-fqaaa-aaaaa-aaaaq-cai trapped explicitly: Panicked at 'called Result::unwrap() on an Err value: TryFromJsValueError("Could not parse bigint to u128")', src/src/lib.rs:678:797"

[lastmjs]

I just tried this example out and called fac 50 and received:

(
  30_414_093_201_713_378_043_612_608_166_064_768_844_377_641_568_960_512_000_000_000_000 : nat,
)

So seems like this issue, at least this specific problem described here, is solved