Add indicator map to area impact view

[vgeorge]

Contributes to #20. This is work in progress.

In this PR we aim to add a choropleth map of the population impacted by the producing area. Other indicators will be implemented in separate tickets as enhancements.

Changes added:

• Include totalpop parameter in vector tiles and single area API endpoints
• Added population layer to <AreaLayer/> component
• Changed machine actions to calculate color ramp dynamically, based on the population of destination areas

Known issues:

• Production area should also display population filling
• Add legend for this map view
• Transition of production->transport area view do not show correct destination areas, while impact->transport does
• Port icons might be too large

Screen capture:

cc @wrynearson @faustoperez

[vgeorge]

Changes added:

• Legend updates according to the current view
• Dynamic color ramp for population legend
• Reduced Port icon size

Quick demo:

How to give feedback:

• Start the app locally
• Click on an area that has flows, like the one in the demo
• Scroll the side panel, legend and map styles should update accordingly

The transition of production->transport area view is displaying all the destination areas, but I couldn't find what is causing the issue yet. I suggest we ticket in separate if this is not blocking.

@wrynearson this is ready for a review.

[wrynearson]

I found a bug when selecting a second producing area while in the impact on people view from a first producing area – the first impact on geometries are shown on the impacts from the second. @vgeorge and I discussed this just now.

[vgeorge]

@wrynearson I added a change to address the issue you found. I also included an empty state to make it clear when no flows are available for an area (contributes to #85). It says "Go to World View" instead of the Figma design’s "Go back" because the user might be accessing the area URL directly, so there may be no browser history to return to. I won't be adding more features to this PR, this is ready for a final review.

[vgeorge]

@wrynearson and I reviewed this together and decided that it is ready to merge.