simplify Membership handlers

Cargo.lock

pallets/duniter-wot/src/lib.rs

pallets/duniter-wot/src/mock.rs

pallets/identity/src/lib.rs

pallets/membership/src/mock.rs

primitives/membership/src/lib.rs

primitives/membership/src/traits.rs

runtime/common/Cargo.toml

runtime/common/src/handlers.rs

runtime/common/src/pallets_config.rs