grandpa: report equivocations with unsigned extrinsics (#6656)

* grandpa: use unsigned extrinsics for equivocation reporting

* grandpa: allow signed reports as well

* grandpa: change runtime api for submitting unsigned extrinsics

* grandpa: fix tests

* grandpa: add test for unsigned validation

* grandpa: add benchmark for equivocation proof checking

* offences: fix grandpa benchmark

* grandpa: add proper weight for equivocation reporting extrinsic

* grandpa: fix weight unit

substrate/client/finality-grandpa/src/environment.rs

@@ -515,12 +515,14 @@ where
 			equivocation,
 		);
 
-		self.client.runtime_api()
-			.submit_report_equivocation_extrinsic(
+		self.client
+			.runtime_api()
+			.submit_report_equivocation_unsigned_extrinsic(
 				&BlockId::Hash(best_header.hash()),
 				equivocation_proof,
 				key_owner_proof,
-			).map_err(Error::Client)?;
+			)
+			.map_err(Error::Client)?;
 
 		Ok(())
 	}

substrate/client/finality-grandpa/src/tests.rs

@@ -217,7 +217,7 @@ sp_api::mock_impl_runtime_apis! {
 			self.inner.genesis_authorities.clone()
 		}
 
-		fn submit_report_equivocation_extrinsic(
+		fn submit_report_equivocation_unsigned_extrinsic(
 			_equivocation_proof: EquivocationProof<Hash, BlockNumber>,
 			_key_owner_proof: OpaqueKeyOwnershipProof,
 		) -> Option<()> {