rust_decimal only supports precision less than 28

[Xuanwo]

rust_decimal looks promising but only supports precision less than 28, while the Iceberg spec requires 38. It's possible for an Iceberg table to contain a decimal value that exceeds this range.

I have initiated a discussion with the upstream to explore potential extensions. However, if we can't find an adequate solution, we might need to switch from rust_decimal to other crates that can support decimal(37, 10).