Remove remaining direct uses of `mp_obj_property_t`

We prefer MP_PROPERTY_GETTER and MP_PROPERTY_GETSET, as these can save flash space on some ports and are also more self explanatory

There's not currently a macro for a property that supports deletion. If there's some rare property that supports deletion, we should introduce and use MP_PROPERTY_GETSETDEL for it (albeit maybe with a better name)