Fix lots of clippy lints

src/client_server/alias.rs

src/client_server/directory.rs

src/client_server/membership.rs

src/client_server/session.rs

src/client_server/sync.rs

src/database/appservice.rs

src/database/globals.rs

src/database/key_backups.rs

src/database/media.rs

src/database/pusher.rs

src/database/rooms.rs

src/database/rooms/edus.rs

src/database/transaction_ids.rs

src/database/uiaa.rs

src/database/users.rs

src/server_server.rs

src/utils.rs