Refactor DB-Access so schema can be specified in Config

[silvanheller]

Ideally, the Cottontail Access Layer would be refactored so that the schema to be used (currently cineast) can be specified in the config. This would mean we could write tests using the "real" database names and eliminate the hypothetical user error where tests are run against a productive database.

For new Contributors

Feel free to set up the stack: https://vitrivr.org/getting_started.html. Afterwards, have a look at the implementation suggestion above and feel free to get started.

A starting point in the code would be the unit-tests for the database layer at https://github.com/vitrivr/cineast/tree/master/cineast-core/src/test/java/org/vitrivr/cineast/core/db