`LocalChain` with hardwired genesis block #4178

Job	Run time
Check WASM	1m 31s
Check no_std	45s
Build and test (stable, true, --no-default-features)	5m 23s
Build and test (stable, true, --all-features)	5m 28s
clippy_check	1m 15s
Build and test (1.57.0, --no-default-features)	5m 24s
Rust fmt	9s
Build and test (1.57.0, --all-features)	5m 19s
	25m 14s

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