Deploy to test environment & introduce environment e2e smoke tests

[ynnckth]

Immediately after deploying to a test environment we want to trigger a set of non-intrusive (read-only) environment e2e smoke tests against that deployed environment.

This is part of a continuous delivery pipeline and should be a pre-condition for an automated production release.

TODO:

• Check if should reuse existing cypress tests for this or create separate set of tests
• Check if tests should really be read-only or if we can actually place orders for a test user and add logic to flag/ignore such orders in the backend. This would give more certainty that the system still works.

[ynnckth]

Consider Heroku free tier dockerized deployment for backend and github pages for frontend