get_by_subject action is configured as get? true but does not have any arguments or filters

[zachdaniel]

The get_by_subject action currently requires that you filter by primary key when running the action. Technically the action just "reads whatever". This is not a security issue, but the issue becomes apparent when exposing the action in ash_admin, because it accepts no inputs and therefore fails because too many entries would be returned. The action should either take specific arguments and/or we should just require that a primary read action exists and use that instead of our own get_by_subject action.

[jimsynz]

Can you tell that it was the first time I had ever used a read action? lol. I don't think it would be a breaking change to make it actually take the argument and work correctly as it's always called via AshAuthentication.subject_to_user/2..3 anyway.