Use macros to define enum helper methods

[DaughterOfMars]

Description

Some enums don't use the def_is_as_into_opt macro in the SDK. We should add these definitions and then we can use them in the FFI.

[thibault-martinez]

e.g. crates/iota-sdk-ffi/src/types/crypto/multisig.rs

[thibault-martinez]

Closed by #112