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/bin/node/testing/src/keyring.rs

@@ -77,7 +77,6 @@ pub fn signed_extra(nonce: Index, extra_fee: Balance) -> SignedExtra {
 		frame_system::CheckNonce::from(nonce),
 		frame_system::CheckWeight::new(),
 		pallet_transaction_payment::ChargeTransactionPayment::from(extra_fee),
-		pallet_grandpa::ValidateEquivocationReport::new(),
 	)
 }