Feature Request: Picking a specific hotspot to see the mapped locations it has witnessed.

As the title suggests, I think a great feature in helping hotspot owners view their functional coverage would be to select an individual hotspot (or group of hotspots/wallet) and have it highlight the locations it has witnessed a mapper send data from.

This data could be presented in several ways:
1. As concentric circles surrounding the chosen hotspot to represent signal strength surround the hotspot.
2. As a heat map to show areas where a hotspot is lacking coverage, possibly due to line of site issues.
3. Individual data points for each of the locations where a mapper has been heard.

I feel like presenting the collected data in this way could help hotspot owners and mappers better understand the benefits or problems of particular hotspot placements and improved antenna setups.

As a secondary benefit, I feel like having this ability could help combat the large scale gaming being seen around the world with hotspots being asserted in areas where they obviously are not. Mapping data would not be conclusive evidence in the short term, but a large enough collection of data in a localized area could help in identifying hotspots that are not physically located where their asserted location says they are.

*edit* I'm still somewhat new to github, so I'm not sure how to give it the 'enhancement' label. Working on that now.
*edit 2* Apparently I don't have permission to add labels.

No files or tests are named. Start by locating the frontend and API paths for hotspot selection and mapper-location data, then decide which visualization is in scope. Done should allow selecting one hotspot or group and showing the locations it has witnessed in a useful map view.

Written by the indexing model from the issue text.