Fast sync (#8884)

* State sync

* Importing state fixes

* Bugfixes

* Sync with proof

* Status reporting

* Unsafe sync mode

* Sync test

* Cleanup

* Apply suggestions from code review

Co-authored-by: cheme <emericchevalier.pro@gmail.com>
Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

* set_genesis_storage

* Extract keys from range proof

* Detect iter completion

* Download and import bodies with fast sync

* Replaced meta updates tuple with a struct

* Fixed reverting finalized state

* Reverted timeout

* Typo

* Doc

* Doc

* Fixed light client test

* Fixed error handling

* Tweaks

* More UpdateMeta changes

* Rename convert_transaction

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Code review suggestions

* Fixed count handling

Co-authored-by: cheme <emericchevalier.pro@gmail.com>
Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/network/src/schema/api.v1.proto

@@ -68,3 +68,28 @@ message BlockData {
 	bytes justifications = 8; // optional
 }
 
+// Request storage data from a peer.
+message StateRequest {
+	// Block header hash.
+	bytes block = 1;
+	// Start from this key. Equivalent to <empty bytes> if omitted.
+	bytes start = 2; // optional
+	// if 'true' indicates that response should contain raw key-values, rather than proof.
+	bool no_proof = 3;
+}
+
+message StateResponse {
+	// A collection of keys-values. Only populated if `no_proof` is `true`
+	repeated StateEntry entries = 1;
+	// If `no_proof` is false in request, this contains proof nodes.
+	bytes proof = 2;
+	// Set to true when there are no more keys to return.
+	bool complete = 3;
+}
+
+// A key-value pair
+message StateEntry {
+	bytes key = 1;
+	bytes value = 2;
+}
+