Update configuration for new version of sociallogin

The newest version of sociallogin has a new way of configuring custom oauth providers. Old config:

            "custom_oidc_providers": "[{\"name\":\"oas\",\"title\":\"OpenAppStack\",\"authorizeUrl\":\"https:\\\/\\\/sso.demo.openappstack.net\\\/oauth2\\\/auth\",\"tokenUrl\":\"https:\\\/\\\/sso.demo.openappstack.net\\\/oauth2\\\/token\",\"userInfoUrl\":\"https:\\\/\\\/sso.demo.openappstack.net\\\/userinfo\",\"logoutUrl\":\"\",\"clientId\":\"nextcloud\",\"clientSecret\":\"GIEFgeQxfVHbayHcVClJ\",\"scope\":\"openid profile email openappstack_roles\",\"groupsClaim\":\"openappstack_roles\",\"style\":\"\",\"defaultGroup\":\"\",\"groupMapping\":{\"admin\":\"admin\"}}]",

New config:

            "custom_providers": "{\"custom_oidc\":[{\"name\":\"test\",\"title\":\"Test\",\"authorizeUrl\":\"https:\\\/\\\/example.com\",\"tokenUrl\":\"https:\\\/\\\/example.com\",\"userInfoUrl\":\"https:\\\/\\\/example.com\",\"logoutUrl\":\"https:\\\/\\\/example.com\",\"clientId\":\"tsra\",\"clientSecret\":\"tsra\",\"scope\":\"tsra\",\"groupsClaim\":\"\",\"style\":\"\",\"defaultGroup\":\"\"}]}",

It looks like everything can stay the same, except that we need to use custom_providers.custom_oidc instead of custom_oidc_providers.