common: Replace CcNumberList with CcNumberRow

CcNumberList is nice, but it's main (only?) use is inside an AdwComboRow. So, in order to make it easier to use for everyone, let's just remove the GListModel implementation, and instead define a new CcNumberRow.

This is just a row based on AdwComboRow, with a GListStore underneath that stores CcNumberObject. There's no more need as well to use GtkExpression directly, as a new value-type property is used to specify the meaning of values in the row. Furthermore, since CcNumberRow is often used to bind a GSettings key, there's now a way to automatically bind that with a single function.

The privacy/screen use of CcNumberList is changed to CcNumberRow, and that really shows the benefit of CcNumberRow over CcNumberList.