Split search results into 3 sections: areas, hucs, communities

[brucecrevensten]

Closes #564
Closes #434

Env:

export RASDAMAN_URL=https://apollo.snap.uaf.edu/rasdaman/ows
export SNAP_API_URL=http://development.earthmaps.io/

Testing:

• Click somewhere in AK on the map. Observe that the results now have 3 sections: areas, HUCs, communities.
• Also observe that HUC8 are now labeled (see image below) -- previously it just said HUC, not HUC8 (but HUC10 was labeled, see detail in Update search result section to better-label certain elements #434)
• But also click somewhere where there aren't HUCs -- in Canada, farther east. The HUC section/header should be omitted.