Split append_pdu -> append_pdu and build_and_append

Cargo.lock

src/client_server/account.rs

src/client_server/membership.rs

src/client_server/message.rs

src/client_server/profile.rs

src/client_server/redact.rs

src/client_server/room.rs

src/client_server/state.rs

src/database/rooms.rs

src/pdu.rs