Get token if it's previously stored, else prompt user to get one.
get_google_token(shiny_return_token = NULL)
In a shiny session, this is passed instead.
a httr configured option for token For shiny the token is passed from reactive session
Other authentication functions: gar_attach_auto_auth
,
gar_auth_service
, gar_auth
,
gar_auto_auth
, gar_gce_auth
,
token_exists