Inaccurate "failed setup" initializing an account with no feeders

[jhansche]

If login succeeds, but there are no feeders on the account, HA reports "Failed setup, will retry". Logs show there were no failures, and login succeeded, but the feeders array is empty.

This should be an allowed scenario, especially since there are no errors logged for the "Failed setup" condition. There would just be no devices created.

This can be encountered by removing the last feeder from an account that had already been integrated successfully - as if an error is raised, the config flow would prevent adding the integration in the first place.

Once this is resolved, it should allow both scenarios: adding the integration using an account with no feeders associated, and also refreshing an already integrated account after removing the last feeder.

[jhansche]

The fix should be to add the account as a "hub", and 0 or more feeders can be associated with that hub account.