It is not ideal to have the UI split across a semi-stable,
cross-module interface boundary. Non-trivial changes to the UI require
changes to the goa_provider_show_account interface. In fact, we were
already not using it the way it was originally intended to be.
Moreover, it prevents us from having a sufficiently different UI for
certain account types.

Instead, let's just pass a vertical GtkBox to the GoaProvider and let
it fill it up whichever way it wants to.

Bump required GOA version for the new goa_provider_show_account
behaviour.

https://bugzilla.gnome.org/show_bug.cgi?id=769213