Builtins to_bits and to_bytes only work for u128

[shuklaayush]

Aim

Opcodes ToBits and ToRadix cast the input field element to u128 so they don't work for larger field elements

noir/crates/noirc_evaluator/src/ssa/optimizations.rs

Lines 535 to 537 in 545340c

	let args = args.iter().map(|arg| {
	NodeEval::from_id(ctx, *arg).into_const_value().map(|f| f.to_u128())
	});

Expected behavior

The functions should work for all field elements (i.e. up-to 254 bits)

Bug

Casting should be avoided

To reproduce

use dep::std;

fn main() {
    let x1 = 0xffffffffffffffffffffffffffffffff;
    let x2 = 0xffffffffffffffffffffffffffffffffff;

    let x1_bytes = x1.to_le_bytes(32);
    let x2_bytes = x2.to_le_bytes(32);
    std::println(x1_bytes);
    std::println(x2_bytes);

    // This should fail
    assert(x1_bytes[16] == x2_bytes[16]);
}

#[test]
fn test_main() {
    main();
}

Installation method

Compiled from source

Nargo version

nargo 0.5.1 (git version hash: 545340c, is dirty: false)

@noir-lang/noir_wasm version

No response

@noir-lang/barretenberg version

No response

@noir-lang/aztec_backend version

No response

Additional context

No response

Submission Checklist

• Once I hit submit, I will assign this issue to the Project Board with the appropriate tags.