Disable sign-up using Oauth
Disallow signup using oauth provider, e.g. Github.
Therefore, overwrite the authorized_signup_handler
as specified in : https://github.com/inveniosoftware/invenio-oauthclient/blob/2359e19caa9ef1063a4b16f0d1dc648755c5823a/invenio_oauthclient/handlers.py#L276-L358
It is configurable via the OAUTHCLIENT_REMOTE_APPS
configuration variable: https://github.com/inveniosoftware/invenio-oauthclient/blob/2359e19caa9ef1063a4b16f0d1dc648755c5823a/invenio_oauthclient/contrib/github.py#L100-L121