Introduce constants for `expect`

crates/configuration/src/network.rs

crates/configuration/src/shared.rs

crates/configuration/src/shared/constants.rs

crates/configuration/src/shared/helpers.rs

crates/configuration/src/shared/resources.rs

crates/configuration/src/shared/types.rs

...iguration/testing/snapshots/0002-overridden-defaults.toml