Raw token leaked into logs by presave hook

Problem/Motivation

Identified by Fable:

  1. Raw token leaked into logs by the FCM presave hook (contradicts the module's own redaction policy).
  FirebasePhpIntegrationHooks::pnRegistrationTokenPresave()
  (submodules/firebase_php_integration/src/Hook/FirebasePhpIntegrationHooks.php:36) throws with the raw token embedded:
  "...Failed token: {$token_to_validate}". When this fires during user.add_push_token, the \Throwable catch in
  AddPushToken.php:100 logs the full exception to watchdog, so the raw registration token lands in the database log.
  firebase_php goes to great lengths to hash tokens everywhere else (hashTokenForLog()); this one path defeats that. It
  can also surface on-screen if the exception bubbles up through the admin entity form. Recommend hashing the token in the
  exception message.