check_verified_properties(): Don't ignore fails of Peerstate::set_verified()

- Return Result from set_verified() so that it can't be missed.
- Pass Fingerprint to set_verified() by value to avoid cloning it inside. This optimises out an
  extra clone() if we already have a value that can be moved at the caller side. However, this may
  add an extra clone() if set_verified() fails, but let's not optimise the fail scenario.

src/receive_imf.rs

@@ -2178,10 +2178,10 @@ async fn check_verified_properties(
                     if let Some(fp) = fp {
                         peerstate.set_verified(
                             PeerstateKeyType::GossipKey,
-                            &fp,
+                            fp,
                             PeerstateVerifiedStatus::BidirectVerified,
                             contact.get_addr().to_owned(),
-                        );
+                        )?;
                         peerstate.save_to_db(&context.sql).await?;
                         is_verified = true;
                     }