Add missing properties to Auth functions context

[samtstern]

Description

Fixes #3536

Scenarios Tested

I created a simple function and triggered it in the Emulators UI:

const functions = require("firebase-functions");

exports.helloWorld = functions.auth.user().onCreate(async (user, ctx) => {
  console.log(JSON.stringify(ctx, undefined, 2));
});

The logs are correct:

>  {
>    "eventId": "d01d812f-03b5-4731-98c2-d539f4cb606f",
>    "eventType": "google.firebase.auth.user.create",
>    "resource": {
>      "service": "firebaseauth.googleapis.com",
>      "name": "projects/demo-project-12345"
>    },
>    "params": {},
>    "timestamp": "2021-06-30T13:45:49.161Z"
>  }

I also deployed a function to production to see the behavior and here is the context payload:

{
  "eventId":"2bcd79bb-dd0d-45b7-85f7-1a51b0b00e5a",
  "eventType":"google.firebase.auth.user.create",
  "notSupported":{},
  "resource":{
    "service":"firebaseauth.googleapis.com",
    "name":"projects/fir-dumpster"
  },
  "timestamp":"2021-07-01T16:51:17.729Z",
  "params":{}
} 

Sample Commands

N/A

[yuchenshi]

Shall this include the user id? I'm not sure what the production behavior actually is though

[samtstern]

I was just following the docs here, but I will deploy a function quickly to confirm:
https://firebase.google.com/docs/reference/functions/cloud_functions_.eventcontext#resource

[samtstern]

Updated the description with a production payload.