Add concern to filter by date ranges in gobierto_people controllers
user
```ruby
module GobiertoPeople
  module DatesRangeHelper
    extend ActiveSupport::Concern

    included do
      helper_method :dates_range?, :filter_start_date, :filter_end_date
    end

    def filter_start_date
      date_from_param_or_session(:start_date, empty_date_range_param?) if site_configuration_dates_range?
    end

    def filter_end_date
      date_from_param_or_session(:end_date, empty_date_range_param?) if site_configuration_dates_range?
    end

    def site_configuration_dates_range?
      site_configuration_date_range.values.compact.present?
    end

    def empty_date_range_param?
      (params.keys & ["start_date", "end_date"]).empty?
    end

    private

    def site_configuration_date_range
      @site_configuration_date_range ||= { start_date: parse_date(current_site.configuration.configuration_variables["gobierto_people_default_filter_start_date"]),
                                           end_date: parse_date(current_site.configuration.configuration_variables["gobierto_people_default_filter_end_date"]) }
    end

    def parse_date(date)
      return unless date
      Time.zone.parse(date)
    rescue ArgumentError
      nil
    end

    def date_from_param_or_session(param, use_default)
      date = if params[param].present?
               Time.zone.parse(params[param])
             else
               use_default ? site_configuration_date_range[param] :nil
             end
      session[param] = date
    rescue ArgumentError
      default_value
    end
  end
end
```
assistant