Support custom genesis block (#12291)

* Set genesis block data using the built genesis block

* Make resolve_state_version_from_wasm a separate function and some small refactorings

Useful for the commit following.

* Introduce trait BuildGenesisBlock

Substrate users can use this trait to implement their custom genesis block when constructing the
client.

* Make call_executor test compile

* cargo +nightly fmt --all

* Fix test

* Remove unnecessary clone

* FMT

* Apply review suggestions

* Revert changes to new_full_client() and new_full_parts() signature

* Remove needless `Block` type in `resolve_state_version_from_wasm`

substrate/client/service/src/config.rs

@@ -34,6 +34,7 @@ pub use sc_network_common::{
 
 use prometheus_endpoint::Registry;
 use sc_chain_spec::ChainSpec;
+use sc_network::config::SyncMode;
 pub use sc_telemetry::TelemetryEndpoints;
 pub use sc_transaction_pool::Options as TransactionPoolOptions;
 use sp_core::crypto::SecretString;
@@ -238,6 +239,22 @@ impl Configuration {
 		};
 		ProtocolId::from(protocol_id_full)
 	}
+
+	/// Returns true if the genesis state writting will be skipped while initializing the genesis
+	/// block.
+	pub fn no_genesis(&self) -> bool {
+		matches!(self.network.sync_mode, SyncMode::Fast { .. } | SyncMode::Warp { .. })
+	}
+
+	/// Returns the database config for creating the backend.
+	pub fn db_config(&self) -> sc_client_db::DatabaseSettings {
+		sc_client_db::DatabaseSettings {
+			trie_cache_maximum_size: self.trie_cache_maximum_size,
+			state_pruning: self.state_pruning.clone(),
+			source: self.database.clone(),
+			blocks_pruning: self.blocks_pruning,
+		}
+	}
 }
 
 /// Available RPC methods.