Get Postgres docker container up and running as an option for local dev database

[BirdTho]

Needs to be optionally started separately from other docker images
Needs readme.md updates
should be PostGIS docker container
Should publish a connection string on command
Should point to some locally downloaded database
Locally downloaded database image should be in .gitignore

[zeffirara]

This could be done via a docker-compose.yml file which could set up and manage all dependencies as separate containers, which could also be used for running integration tests. Something like this: https://wkrzywiec.medium.com/how-to-run-database-backend-and-frontend-in-a-single-click-with-docker-compose-4bcda66f6de.