Create an `alerts_dashboard` view for visualizing change detection alerts

[rudokemper]

Now that we have change detection alerts flowing into partner data warehouses, let's create a bespoke dashboard view that visualizes change detection alerts on contextual maps (with useful data such as historical change detection, concessions data, and more) and provides links to download map resources (generated by GCCD) for each alert.

[rudokemper]

Features for an MVP:

• [x] Differentiate latest import batch of alerts in a different color from the rest
  • [x] Add pulsating circles around latest alerts as map marker
• [x] Change outline of selectedFeature layer (when clicked)
• [x] Alerts are clickable and properties plus links (to preview HTML maps, Mapeo map package downloads) are shown in a sidebar
  • [x] Add coordinates to FeaturePopup
  • [x] Ability to download as GeoJSON or CSV
• [x] Overview panel showing some basic statistics - number of alerts in the last / most recent month, number of alerts total, number of hectares
  • [x] Ability to download all alerts as GeoJSON or CSV.

Future:

• [x] Stretch goal: date range filter to allow the user to filter the alerts
• [x] Ability to batch download a selection of alerts (i.e. what is shown on the screen after filtering has been applied)
• [ ] Ability to mark alerts as having been verified (e.g. ground truthed, inspected, or socialized within the community) and show a visual cue somewhere on the dashboard.