Situational Awareness Widget - allow multiple layers under one tab

[AnneShanahan]

Add the ability to use multiple layers under the same tab within the situational awareness widget.

For example, if we wish to report impacted lifelines within an incident area we currently need to have a seperate tab for water mains, water pump stations, water reseviors as they are different layers. I'd like to report them under the one tab of 'Water'. In the screengrab below I'd like to select more than one from the drop down list.