Refactor `verify_u256_to_native_amount` to be a wrapper function on `verify_u128_to_native_amount`

[partylikeits1983]

As discussed offline, we should have better error handling when the asset amount when moving assets from EVM to Miden is larger than $2^{128}$.

Additionally, verify_u256_to_native_amount_conversion should be refactored to call verify_u128_to_native_amount_conversion. The error ERR_X_TOO_LARGE should be called in the verify_u256_to_native_amount_conversion procedure if $X$ is larger than $2^{128}$.

The ERR_X_TOO_LARGE error string should be more descriptive, e.g. "The agglayer bridge in u256 value is larger than 2**128 and cannot be verifiably scaled to u64".

[mmagician]

closed in #2504