BiGCZ: Clear results from map after leaving search page

[arottersman]

Overview

The BiG-CZ data catalog results would remain on the map even after you'd navigated back to the splash page/analyze.

Connects #2054

Demo

Testing Instructions

• Pull and bundle
• Search for something that yields shapes in WDC and cinergi
• Confirm they clear if you use the browser back navigation or click the header to go to the splash
• Confirm you can still search another shape

[rajadain]

Taking a look now.

[rajadain]

If I click the home button and leave before results have finished fetching, when they do finally finish I see this error in the console:

[rajadain]

This works great, except for that error mentioned above. I think there's enough bandwidth to handle that in this card, but if it feels too onerous feel free to offload to a future issue.

[rajadain]

Consider also settings dataCatalogActiveResult to null for completeness:

App.map.set({
  dataCatalogResults: null,
  dataCatalogActiveResult: null,
});

[arottersman]

I rebased on #2110 to cancel searches on clean up (87ccb91). Now only the last three commits pertain to this PR.

[rajadain]

Great work! Tested, works splendidly.

[arottersman]

Rebased on develop. Going to merge!