* Move multiple defaults from entrypoint script to cfg.lua files.
* Move remaining defaults from entrypoint script to cfg.lua files.
* Update postgres version in tests
* Register users with prosodyctl in tests
* Replace 'docker-compose' with 'docker compose'
* Add environment variables for Database configuration.
* Install postgres and mysql dependencies.
* Test refactoring
* Run tests for prosody with postgres and also for prosody with sqlite.
* Add tests that check if postgres or sqlite is used.