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/authority-discovery/src/worker/tests.rs

@@ -69,6 +69,7 @@ impl<Block: BlockT> HeaderBackend<Block> for TestApi {
 			finalized_number: Zero::zero(),
 			genesis_hash: Default::default(),
 			number_leaves: Default::default(),
+			finalized_state: None,
 		}
 	}