Improve event sent from list on hover/click

[QuCMGisaia]

Currently, the list emits event when an item is hovered or clicked using the following structure:

export interface ElementIdentifier {
  idFieldName: string;
  idValue: string;
}

To differentiate between the different behaviors, the idValue is modified by adding 'leave-' or 'click-' in front. The MapContributor then processes that information in the case of highlighted elements.

It could be simplified by just adding an 'event' attribute to the ElementIdentifier oject.