Add April 17th robberies map

[michplunkett]

What does this PR do?

How was the functionality tested and verified?

All steps should be completed in the order presented, and you should not move on to the next step until the previous is completed.

• [x] The title of the html page is the same as the chart.
• [x] The meta_data.json file is filled in correctly (the description is a complete sentence, the title is the same as the visual).
• [x] The chart and its associated pages have been minified using the npm run process-visual command.
• [x] This visual was approved by the lead developer.
• [x] The visual was approved by the story's stakeholders.