sc-keystore: Improve weird error message (#10584)

The keystore would print "Invalid password" when a key was stored using an incorrect public key.
This pr improves the error message to communicate better to the user on what is wrong.

substrate/client/keystore/src/local.rs

@@ -503,7 +503,7 @@ impl KeystoreInner {
 		if &pair.public() == public {
 			Ok(Some(pair))
 		} else {
-			Err(Error::InvalidPassword)
+			Err(Error::PublicKeyMismatch)
 		}
 	}