#118: DB cleanup and IT tests addition to CI

[lsulak]

Preparation for #118 - I don't really want to do all the DB setup for tests manually, it's too much effort. I used Flyway to automate it. It's not ideal - the actual data insertions and cleanups after each test - but it's better than it was and we can improve it on the next increment.

What was done:

• DB files (SQL and DDL) were moved and renamed / polished to be compatible with Flyway tool; it seems like a lot of changes and files, but really it was mostly small changes
• I created .github/workflows/integration_tests.yml - but there are many things to improve in the future:
  • test coverage
  • better documentation perhaps (#116)
  • better test isolation - test data init and cleanup (#121)

--

Relates to #118 Relates to #116 Relates to #121 Relates to #19

[github-actions[bot]]

JaCoCo code coverage report - scala 2.13.12

Total Project Coverage	27.94%	:green_apple:

There is no coverage information present for the Files changed

[github-actions[bot]]

JaCoCo code coverage report - scala 2.12.17

Total Project Coverage	27.05%	:green_apple:

There is no coverage information present for the Files changed