BEEFY: define on-chain beefy-genesis and use it to coordinate voter initialization (#13215)

* beefy: add support to configure BEEFY genesis

* client/beefy: more flexible test runtime api

* client/beefy: add tests for custom BEEFY genesis

* client/beefy: ignore old state that didn't account for pallet genesis

* client/beefy: fix clippy

* frame/beefy: default BEEFY-genesis is block One::one()

* frame/beefy: add extra doc comments

---------

Co-authored-by: parity-processbot <>

substrate/test-utils/runtime/src/lib.rs

@@ -973,6 +973,10 @@ cfg_if! {
 			}
 
 			impl beefy_primitives::BeefyApi<Block> for Runtime {
+				fn beefy_genesis() -> Option<BlockNumber> {
+					None
+				}
+
 				fn validator_set() -> Option<beefy_primitives::ValidatorSet<beefy_primitives::crypto::AuthorityId>> {
 					None
 				}