Add confirm command to wallet, and update RPU to check bank for a signature

src/request_processor.rs

@@ -40,6 +40,12 @@ impl RequestProcessor {
                 info!("Response::TransactionCount {:?}", rsp);
                 Some(rsp)
             }
+            Request::GetSignature { signature } => {
+                let signature_status = self.bank.check_signature(&signature);
+                let rsp = (Response::SignatureStatus { signature_status }, rsp_addr);
+                info!("Response::Signature {:?}", rsp);
+                Some(rsp)
+            }
         }
     }