Hidden macro categories API

The MacroCategoryManager role gives access to the list of hidden macro categories.

@Role
public interface MacroCategoryManager
{
    // [...]

    /**
     * @return the set of hidden categories (e.g., "Deprecated, Internal")
     * @since 14.8RC1
     */
    @Unstable
    default Set<String> getHiddenCategories()
    {
        return Set.of();
    }
}