[4.0] Handle Google responses excluding 'name'

[derekmd]

I just had a Google login callback in production throw an exception because the 'name' JSON key was missing in the payload. Generally this would be a full response body:

{
  "id": "1008...",
  "email": "derek...@...",
  "verified_email": true,
  "name": "Derek M...",
  "given_name": "Derek",
  "family_name": "M...",
  "link": "...",
  "picture": "...",
  "locale": "en",
}

But for incomplete (or service migrated?) accounts Google may exclude some keys. I can't find complete documentation covering how this OAuth2 scope is supposed to behave. They only offer a live-fetch form: https://developers.google.com/apis-explorer/#search/userinfo/m/oauth2/v2/oauth2.userinfo.v2.me.get

Socialite's 3.0 branch already handles this field as optional: https://github.com/laravel/socialite/pull/319/files#diff-2adaa1ef0c311c4b988908f120ea7557R84