Add internationalization and language selection to the backend

[0phelia36]

This PR added internationalization for strings to the frontend, however the frontend displays some messages from the backend to users directly, so to fully allow localization of the microlab, this will need to be added to the backend as well. This will be needed to fully complete #250.

PR #246 Also didn't add a language selection functionality, so this will need to be added to the backend config that the frontend can access and set from available options.