`LocalChain` with hardwired genesis block #4217

Job	Run time
Check no_std	49s
Build and test (stable, true, --no-default-features)	2m 1s
Build and test (stable, true, --all-features)	2m 17s
Check WASM	41s
clippy_check	1m 21s
Build and test (1.57.0, --no-default-features)	5m 11s
Build and test (1.57.0, --all-features)	5m 6s
Rust fmt	6s
	17m 32s

Provide feedback