Extract snapshot to own crate (#11010)

* Move snapshot to own crate
Sort out imports

* WIP cargo toml

* Make snapshotting generic over the client
Sort out tests

* Sort out types from blockchain and client

* Sort out sync

* Sort out imports and generics

* Sort out main binary

* Fix sync test-helpers

* Sort out import for secret-store

* Sort out more imports

* Fix easy todos

* cleanup

* Cleanup

* remove unneded workspace member

* cleanup

* Sort out test-helpers dependency on account-db

* Update ethcore/client-traits/src/lib.rs

Co-Authored-By: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Update ethcore/snapshot/Cargo.toml

ethcore/client-traits/src/lib.rs

@@ -29,6 +29,7 @@ use common_types::{
 	blockchain_info::BlockChainInfo,
 	BlockNumber,
 	call_analytics::CallAnalytics,
+	chain_notify::{NewBlocks, ChainMessageType},
 	client_types::Mode,
 	encoded,
 	engines::{epoch::Transition as EpochTransition, machine::Executed},
@@ -40,7 +41,7 @@ use common_types::{
 	pruning_info::PruningInfo,
 	receipt::LocalizedReceipt,
 	trace_filter::Filter as TraceFilter,
-	transaction::{self, LocalizedTransaction, CallError, SignedTransaction},
+	transaction::{self, LocalizedTransaction, CallError, SignedTransaction, UnverifiedTransaction},
 	tree_route::TreeRoute,
 	verification::{VerificationQueueInfo, Unverified},
 };
@@ -119,7 +120,7 @@ pub trait ChainInfo {
 }
 
 /// Provides various information on a block by it's ID
-pub trait BlockInfo {
+pub trait BlockInfo: Send + Sync {
 	/// Get raw block header data by block id.
 	fn block_header(&self, id: BlockId) -> Option<encoded::Header>;
 
@@ -474,3 +475,38 @@ pub trait SnapshotWriter {
 	/// with the chunks written.
 	fn finish(self, manifest: common_types::snapshot::ManifestData) -> std::io::Result<()> where Self: Sized;
 }
+
+
+/// Represents what has to be handled by actor listening to chain events
+pub trait ChainNotify: Send + Sync {
+	/// fires when chain has new blocks.
+	fn new_blocks(&self, _new_blocks: NewBlocks) {
+		// does nothing by default
+	}
+
+	/// fires when chain achieves active mode
+	fn start(&self) {
+		// does nothing by default
+	}
+
+	/// fires when chain achieves passive mode
+	fn stop(&self) {
+		// does nothing by default
+	}
+
+	/// fires when chain broadcasts a message
+	fn broadcast(&self, _message_type: ChainMessageType) {
+		// does nothing by default
+	}
+
+	/// fires when new block is about to be imported
+	/// implementations should be light
+	fn block_pre_import(&self, _bytes: &Bytes, _hash: &H256, _difficulty: &U256) {
+		// does nothing by default
+	}
+
+	/// fires when new transactions are received from a peer
+	fn transactions_received(&self, _txs: &[UnverifiedTransaction], _peer_id: usize) {
+		// does nothing by default
+	}
+}