chore(sc-cli): improve runner and signals (#13688)

* chore(sc-cli): improve runner and signals

* Update client/cli/src/runner.rs

* fmt

---------

Co-authored-by: Bastian Köcher <git@kchr.de>

substrate/client/cli/src/lib.rs

@@ -31,6 +31,7 @@ mod config;
 mod error;
 mod params;
 mod runner;
+mod signals;
 
 pub use arg_enums::*;
 pub use clap;
@@ -41,6 +42,7 @@ pub use params::*;
 pub use runner::*;
 pub use sc_service::{ChainSpec, Role};
 pub use sc_tracing::logging::LoggerBuilder;
+pub use signals::Signals;
 pub use sp_version::RuntimeVersion;
 
 /// Substrate client CLI