Add behaviour to scopelist when parent items have no data (after applying actual content constraints)
the Field filter list is currently empty, because the parent codes (of codes that have values) do not have values themselves. Values thus only appear when using the scopelist.
In order to solve this we need the ability to display the parent codes but disable them.
Disabled filter values (parent items of the list without data but for which children codes have data) are kept visible in the hierarchical list, but change their state: The icon image colour (see #111 (closed)) and the filter value text colour change to grey (same grey as used for the number of hits in brackets in search result page, tbd: Grey text colour to be reviewed and validated for AAA web accessibility). Filter values in such state cannot be selected but the user can navigate to the children.
So for a parent that has no data but its children have data, the parent appears in the list as a non-selectable item, but its "hierarchical arrow" is clickable.
Example: at the root level, there is no data for the"Non-OECD Economies" but children list with data is available: