Developer: Plot firefighter location on the dashboard

This feature should be embedded in the version deployed for the February burn. It should also be updated to fit the look and feel of the long-term dashboard in #80

Current work is in the [dashboard](https://github.com/Code-and-Response/Prometeo/tree/master/dashboard) folder.

It could also benefit from an existing UI library, like [Carbon](https://www.carbondesignsystem.com/data-visualization/dashboards/).