Add location inputs to modal dialog

[ehunter-usgs]

I would be in favor of replacing the four leaflet controls on the map with a single leaflet control that opens a modal dialog.

Inside the pop-up we would have the four options for setting a user's location. This would be a more mobile friendly solution that would more seamlessly scale with the size of the user's screen. It would also provide additional room to explain how the different options work. Each of the controls could be hidden inside a collapsed accordion, with the first option expanded (current location).

After the user selects their location the pop-up should allow for the user to see the location on the map or choose a new location.

We could also use this as an opportunity to update hazdev-location-view to use Google's Material Icons.

[ehunter-usgs]