Silence known deprecation warnings (#2651)

* Silence known deprecation warnings

1. Prefixes known instances of usages of client.backend and client.import_lock with `#[allow(deprecated)]` to silence the warnings. 2. Remove file-global `#![allow(deprecated)]` used in these cases. Both to prevent us overlooking externally caused deprecation messages.

* fixing missing ;

* fix missing test cases

* move deprecated markers to make CI happy

* move deprecated markers to make CI happy

* attempt to fix the test

* bumping impl_version of node runtime

* Minor cleanup

substrate/core/finality-grandpa/src/finality_proof.rs

@@ -173,6 +173,7 @@ impl<B, E, Block, RA> network::FinalityProofProvider<Block> for FinalityProofPro
 			})?;
 		match request {
 			FinalityProofRequest::Original(request) => prove_finality::<_, _, GrandpaJustification<Block>>(
+				#[allow(deprecated)]
 				&*self.client.backend().blockchain(),
 				&*self.authority_provider,
 				request.authorities_set_id,