Simplify some Option / Result / ? operator patterns (#8653)

* Simplify some Option / Result / ? operator patterns

When those match a combinator exactly.

Tool-aided by [comby-rust](https://github.com/huitseeker/comby-rust).

* adjust after review

* adjust post-review

substrate/client/peerset/src/peersstate.rs

@@ -272,15 +272,11 @@ impl PeersState {
 			})
 			.map(|(peer_id, _)| peer_id.clone());
 
-		if let Some(peer_id) = outcome {
-			Some(NotConnectedPeer {
+		outcome.map(move |peer_id| NotConnectedPeer {
 				state: self,
 				set,
 				peer_id: Cow::Owned(peer_id),
 			})
-		} else {
-			None
-		}
 	}
 
 	/// Returns `true` if there is a free outgoing slot available related to this set.