add membership removal reasons

pallets/duniter-wot/src/lib.rs

pallets/duniter-wot/src/mock.rs

pallets/duniter-wot/src/tests.rs

pallets/identity/src/lib.rs

pallets/membership/src/lib.rs

runtime/common/src/handlers.rs

runtime/gdev/tests/fixme_tests.rs

runtime/gdev/tests/integration_tests.rs