modulate the map components

[adambreznicky]

right now, we have completely independent components for the geofilter, county coverage, download, and index download maps. these should be reconfigured to in a more modular fashion starting with a shared, basic map component and then plug in the download layers and/or functionality from a separate action or component.

[adambreznicky]

the reference county/quad layers with labels can definitely be split out into a separate component for adding to the map (just like the basemap selector adds those layers to the map) at the very least