sdk: add is_interactive() method Signer trait (#18407)

(cherry picked from commit 2af5ec4f57)

Co-authored-by: Trent Nelson <trent@solana.com>

remote-wallet/src/remote_keypair.rs

@@ -53,6 +53,10 @@ impl Signer for RemoteKeypair {
                 .map_err(|e| e.into()),
         }
     }
+
+    fn is_interactive(&self) -> bool {
+        true
+    }
 }
 
 pub fn generate_remote_keypair(