fix: to-bits and to-radix for > 128 bits

[shuklaayush]

Related issue(s)

Resolves #1311
See #1109 (comment)

Description

Summary of changes

• Avoid casting of opcode arguments to u128 before converting to bits or bytes
• Allow to_radix_base to work for elements close to the modulus

Dependency additions / changes

Test additions / changes

Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt with default settings.
• I have linked this PR to the issue(s) that it resolves.
• I have reviewed the changes on GitHub, line by line.
• I have ensured all changes are covered in the description.

Documentation needs

• This PR requires documentation updates when merged.

Additional context

BEGIN_COMMIT_OVERRIDE
fix(stdlib): support use of to_bits and to_radix for values >128 bits (#1312)
END_COMMIT_OVERRIDE

[guipublic]

I am OK with replacing u128 with field elements for intrinsic arguments, but I am not sure your changes in the overflow check is correct. Could you provide a proof of correctness?

[shuklaayush]

I reverted to the old overflow check based on the comments.

There are also a couple of other issues in the ToBits implementation:

• It ignores the input endianness
• It returns something even if the element wouldn't fit in the input bit_count. This is inconsistent with ToRadix which panics with ArrayOutOfBounds

I guess I can fix these in a follow-up PR once I know what the right behaviour should be.