Display Census Tract

[kmorhun]

This Pull Request:

• Begins addressing Issue #2
• Adds example geojson files to the backend/app/data folder for future use
• Creates a URL and API view for accessing geojson data in the backend
• Displays the 2021 boundaries of Deanwood, Washington DC (Tract 78) on the map-macro page

[anastasia]

This looks great, merging! A couple notes:

• it's good to note in PRs if there are any package changes, that way you give a heads up to your collaborators that they will need to install dependencies. Your PR includes axios so that would just be a small note like "This PR adds the axios package. Must run npm ci on merge".
• Something to think about: we don't want to over-design for an unknown future, but since you are starting to work with exposing census data (to both the frontend and any potential user hitting /api/get_census_data), we can start a discussion about what this could look like in the future. Is this the right endpoint name for a time where we have two or more cities' census data? Maybe something like /api/tracts/deanwood works better? Maybe it's something else?