Let human_address/canonical_address return correct error type to report back to contracts

[webmaster128]

How can the human_address/canonical_address implementations know which go error to send to the contract as a FfiError::UserErr (the user's fault) and which one as a FfiError::Unknown (the system's or backend's fault)?

See also CosmWasm/cosmwasm#397

[ethanfrey]

If we return a GoResult::Other to rust, then it is not due to FFI bindings, but rather due to the go parsing function returning a normal go error: https://github.com/CosmWasm/go-cosmwasm/blob/44f9b89bfd115078e18c74675d1dbe895afcd240/api/callbacks.go#L359

This is exactly related to invalid format/length for address and other stuff that we want to return to the user. In short, always return as a user error.

We need to update the api calls to return user_error here: https://github.com/CosmWasm/go-cosmwasm/blob/524a69c97853fc8d3960be2515b94b191db88863/src/error/go.rs#L89 instead of other, like the rest of the calls

[webmaster128]

Since we convert the error in the general GoResult::into_ffi_result, I think we should split GoResult::Other into GoResult::User (to be passed to the contract if possible) and GoResult::Unknown (erroring at VM level).