Tries to find the path to the _auth0.yml file. First, it tries to get
this info from options(auth0_config_file = ). If this option is NULL
(the default) it tries to find the _auth0.yml within the working
directory. If the file does not exist, it raises an error.
auth0_find_config_file()Character vector of length one contaning the path of the
_auth0.yml file.