grandpa: always create and send justification if there are any subscribers (#6935)

* grandpa: use bytes type for justification rpc notification

* grandpa: always create justification if there are rpc subscribers

* grandpa: wording

* grandpa: replace notify_justification macro with function

* grandpa: prefer Option<&T> over &Option<T>

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

@@ -619,7 +619,6 @@ where
 	Client: crate::ClientForGrandpa<Block, BE>,
 	NumberFor<Block>: finality_grandpa::BlockNumberOps,
 {
-
 	/// Import a block justification and finalize the block.
 	///
 	/// If `enacts_change` is set to true, then finalizing this block *must*
@@ -653,7 +652,7 @@ where
 			number,
 			justification.into(),
 			initial_sync,
-			&Some(self.justification_sender.clone()),
+			Some(&self.justification_sender),
 		);
 
 		match result {