Add missing WebpushFcnOptions entity

Describe your environment

  • Operating System version: Windows 10
  • Firebase SDK version: latest
  • Library version: any
  • Firebase Product: messaging

Describe the problem

Documentation for Firebase HTTP v1 API says that WebpushConfig can contain WebpushFcmOptions representing options for features provided by the FCM SDK for Web.
But Java client for Firebase Admin SDK doesn't include WebpushFcmOptions, so it's not possible to use this API feature.

Suggestion

I suggest to implement WebpushFcmOptions class and include it in WebpushConfig.