chore: deployment workflows

[nunocaseiro]

Relates to #104

Proposed Changes

• Github workflows to build the backend and frontend docker image then push it to a container registery and finally update the staging app only when the code is merged into the main branch
• Docker compose with azure environment variables
• Frontend and backend docker files updated to include azure env vars
• Database connection string updated based on environment

This pull request is intendend to close #104

[serrovsky]

Docker images names suggestion