feat: add signet-host-reth crate with RethHostNotifier #467

Job	Run time
rust-library-base / Feature Checks	5m 40s
rust-library-base / Base Checks / Clippy	4m 9s
rust-library-base / Base Checks / Docs	4m 9s
rust-library-base / Base Checks / Test Suite	9m 11s
rust-library-base / Base Checks / Rustfmt	38s
rust-library-base / Base Checks / doctest	5m 35s
	29m 22s

Provide feedback