Add .devcontainer (#1032)

Adds support for [devcontainers](https://containers.dev/), this should
make onboarding easier and should allow (especially simpler)
contributions entirely online via Github Codespaces 🚀

docker-compose.yml

@@ -12,5 +12,5 @@ services:
       - '3001:3001'
     volumes:
       - '.:/app'
-    restart: no
+    restart: 'no'