Nat & Int do not support binary encoders

[rupansh-sekar-yral]

Nat & Int use deserialize_any in their de-serialization implementation: https://github.com/dfinity/candid/blob/master/rust/candid/src/types/number.rs#L155 https://github.com/dfinity/candid/blob/master/rust/candid/src/types/number.rs#L205

most binary encoding libraries do not support deserialize_any, example

bincode: https://github.com/bincode-org/bincode
postcard: https://github.com/jamesmunns/postcard

Is using BigUint/BigInt the only way?