Feature: Migrate from Google maps to Leaflet

[favillat]

Feature Suggestion

Describe the Feature

use leaflet as a good open source alternative to google maps, mainly so we don't have to worry about API keys and for greater customization (dark mode maps lets go).

[ETSells]

+1 from firmware here. I like a lot of the available features I'm seeing.

[ETSells]

Recommend also considering what we should do when offline. I would expect slow/no internet access at launch sites where we're deploying the app.