Add U240 params

[olehmisar]

Problem

U240 would be enough for most EVM token amount operations, so in Noir it can be represented with only 2 limbs (vs 3 limbs for U256).

Happy Case

Implement bignum::fields::U240Params

Workaround

None

Workaround Description

No response

Additional Context

No response

Project Impact

Nice-to-have

Blocker Context

No response

Would you like to submit a PR for this Issue?

None

Support Needs

No response

[olehmisar]

also, would be interesting to see the benchmarks of std::U128 vs bignum::U240 as they both consist of 2 limbs(except U128 limbs are of type u64)