Updating user attributes on oauth login (#5324)

Moving update function to app package
Fixing duplicate userID on create user test

i18n/en.json

@@ -2339,6 +2339,10 @@
     "id": "api.user.create_oauth_user.not_available.app_error",
     "translation": "{{.Service}} SSO through OAuth 2.0 not available on this server"
   },
+  {
+    "id": "api.user.update_oauth_user_attrs.get_user.app_error",
+    "translation": "Could not get user from {{.Service}} user object"
+  },
   {
     "id": "api.user.create_profile_image.default_font.app_error",
     "translation": "Could not create default profile image font"