vdk-oracle: run tests in CI using testcontainers

[DeltaMichael]

Overview

For development, vdk-oracle tests were run by connecting to an Oracle Autonomous Database using Oracle Cloud. The free Oracle DB doesn't run on M1 Macbooks, neither does their docker image, so this was the only option.

This is not feasible for testing in CI, so we should have a testcontainers setup like we do for other plugin tests. Oracle provide a docker image we should be able to run in CI.

Oracle DB Free Container

Acceptance Criteria

1. Set up Oracle DB with test containers as part of the vdk-oracle test suite
2. Set up tests to connect to the DB
3. Tests run in CI and pass