Add apple-app-site-association to support Apple Passkey feature

[kj84park]

In order to provide iOS's Apple passkey functionality, the RP must provide an apple-app-site-association page.

• References

{
  "webcredentials": {
    "apps": [
      "YOUR_APPLE_DEVELOPER_TEAM_ID.com.example.sample.Passkey"
    ]
  }
}

Supporting Associated Domains Supporting Passkeys