Setup DB migration

[sarahsporck]

Is your feature request related to a problem? Please describe.
At some point we will need to make DB migrations. Research possible solutions, test them and then create a draft PR so it can be evaluated.

Describe the solution you'd like

• some already existing tooling like Flyway

Describe alternatives you've considered

Additional context

• exposed ticket: Database Migrations JetBrains/Exposed#165
• possible integration with flyway: https://www.thebookofjoel.com/kotlin-ktor-exposed-postgres
• and also with flyway: https://bettercoding.dev/kotlin/tutorial-exposed-generation-flyway/