[6.x] Fix login and passkeys

[jasonvarga]

• Both AbortError and NotAllowedError are expected states and should not result in "Authentication failed" being shown.
  • AbortError happens when the ceremony is cancelled (e.g. navigating away or starting a new authentication)
  • NotAllowedError is when the user dismisses the popup
• Fixed the Passkey button click handler passing a MouseEvent as the useBrowserAutofill parameter, which caused it
  to use the wrong authentication mode
• Cancel any pending WebAuthn ceremony when the login page unmounts (e.g. you navigate away)
  • This was not strictly necessary as it would get aborted on return, which we now silently ignore, but its better to cancel when it's supposed to.

Fixes #13753