supervisor: update to allow autorun configuration
This adds possibility to completely configure updater (autorun) trough supervisor. Advantage of this is that supervisor is the only place that defines uci configuration for updater (at least if we are talking about autorun) and because of that same API can be used on top of generally different configuration. This is handy because of back compatibility with Turris OS 3.x and introduced cleanup in Turris OS 4.x.